Same happens to me  a bit when casting minnow lures for tailor.  Lately I've had much fewer knots in the braid after I shortened my leader to about 1m lenght, so less chance of the leader knot catching on the runners when casting. Using a rod withslightly larger rather than smaller runners also helped. The other thing that seemed to help was closing the bail after the cast then pulling the line tight to make sure there was no slack or loop at the spool.  Just doing those two things  have made the problem go away for that style of casting for me.

Here is a link that covers a few things that can help also;   https://www.saltstrong.com/articles/fix-prevent-wind-knots/

 too much line on the reel ...should not happen if heavier  sinker ... be sure to clip bail arm as quickly as possible after rig has entered the water . i usually feather the line with my finger just at the point of entering into the water 

 there is no such thing as a wind knot - its all formed by slack in the line - search you tube , some good explanations and tips

Tips:

• Don't overfill the spool with line. Remove some line if you need to. 
• Close the bail manually after casting.  Don't crank the handle to close the bail.
• Once you've closed the bail, check that the line coming off the spool is somewhat roughly lined up with the line roller.  If the line roller and where the line is coming off the spool are badly mialigned, when you start winding in it creates a diagonal run of line across the spool, which may not release at the same rate when you cast through it in the future.  Let a few extra loops of line out if you need to, so the line is kept relatively evenly wound.  It doesn't have to be perfect, you just want to avoid the extremes.
• Slightly tension the line, pinching it really lightly and sliding your hand up toward the first guide to make sure there's not a slack loop near the spool about to get trapped when you start winding on more line. Then start winding in.
• If you're running a wind-on leader, use a low profile knot like the FG knot to connect the braid to the mono
• If you're running really heavy leader or using a bulkier connection knot, some people find it works better to have the leader not quite long enough to wind onto the spool, so the connecting knot stays between the reel and the first guide, or between the first and second guides.  You should still use an FG knot or similarly slim connection.

Line twist is a huge contributor of wind knots. Twist a piece of braid 20 times and then see what happens when you slack it off. When you fire a lure or rig off it doesn't fly at the same speed the whole way. As the rig or lure slows down, the line creates a bit of slack and any twists in the line will become evident. Happens to me more on windy days than calm days. 

How to avoid - properly maintain your line roller bearing or line roller bushing. Run a swivel where possible. Try not to run rolling rigs in the surf that can spin 30 times while you've got your bait set. 

how to reduce once you've already got it - get those twists out of your line by spooling it on and off a few times with a heavy weight and a swivel on the end. I'd possible, keep the line between your thumb and forefinger when you're spoiling it on and you'll feel the twists transfer up towards the terminal tackle end. 

If all else fails just crack the shits, cut it all off in a fit of rage and watch a beautiful sunset 

Most the key issues have been raised above, most likely your issue is with loose line on the retrieve I see it a lot when I do lure casting on my fishing tours. A little extra tension from the fingers when a wave surfs the lure can make a big difference. Also consider the size / weight of the lure a heavier lure will pull the line off cleaner and offer more resistance on the wind back in, seating the line more firmly. As you get better at managing the line they won't be a issue any more and you can move to lighter lures. 50lb is very heavy for lure casting and certainly wont help with light lures, you will have to cast too hard to try get the distance. A lighter line class will get further with less effort, when not putting so much oomf into the cast there will be less knots too. 

Thanks for all the advice and definitley a few things there that I will keep in mind!!

Certainly don't think it is from too much line on the spool as I have had to cut a heap off from ongoing knots and hasn't resolved. I'll be certain to try and keep more tension on line when retrieving and will also shorten the leader to try and stop the FG catching on the runners and see if that helps :) 

What sort of lure casting do you do ?

 I reckon 50lb is too thick and heavy for a 5500 size reel if it is in the new Daiwa LT range ? If it is the Pre-2019 daiwa range then 50lb is fine. 

 Most factors have been mentioned above so I'll just add a couple:

1. Reduce your braid to 30lb and see how it goes ? Some braid are thick and nasty and give lots of problems.

2. Leader diameter vs braid diameter if you have windon leader with FG knot. I notice if you are using too thick a leader, it will inevitably kink where the FG knot is, resulting in wind knot. 

3. Try supple mono leader rather than stiff ones like Fluro Carbon leader.

4. Get a rod with Fuji K guides, reduce the likelihood of windknot.

5. I get wind knots when I am fishing blooping style surface poppers more simply because of the slack line caused by wind after blooping the lure, when pausing.  If your reel retrieve speed is not fast enough to retrieve the line onto the spool before the slack is formed, it will result in a slack being wound onto the spool. This slack is the culprit for wind knot on the next cast. Use a reel with higher retrieve ratio speed to resolve this. This are the reels with "H" or "XG" in their model name. Eg. TwinPower 4000XG.

Pack braid on tight when spooling .

never had issues .. cheers pirate 

 What is a leader? Of course I know what a leader is but in over 50 years of fishing never used one and see no reason to start now.

I use braid on a 499 Mitchell on a 12 foot Butterworth and never have a problem in either spinning with metals or bottom fishing , the trick is to slow the line down at the last second of the cast and not allow any slack