Thanks for your replies. So another strange twist. I changed my formation to a 4-4-2 and the possession went back to normal. This was not my strongest team as I have built it for a V formation. At at half time it was 1-1. I changed the formation and players back to my normal formation and I won the game 3-1 with 55% possession. Weird or what....

Question - Was this a bug where the system thought I had an illegal formation, and changing my formation up unblocked it.

Or

Does the software penalize you if you never change your formation?