pixel_player541254191 I have to ask the obvious question, did you use the "Trophy Icon" to see your score / finishing position and hit "Collect" to gather the coins? You have to take explicit action to get the coins to be credited to your game, nothing automatically gathers your winnings.
You have approximately 12 hours from the end of the competition, 12:00 UTC Thursday until 00:00 UTC Friday. Afterwards the trophy icon either disappears for a bit or transitions from "Finished" to "Next Competition Starts in X hours Y minutes" and you can no longer collect coins from the previous competition.
Does this explain why you do not have your coins?