My "Mini Camp" was supposed to release my new players on Day 28 of the last season. On Day 27, I started the upgrade of the facility.
It informed me that the players will be available after the upgrade will be completed. On Day 1 of this season, when there was one day left on the upgrade to complete, I used the "Speed Up" feature to finish the build. It then says "2 new players will be released in 20 days", but the players supposed to be released upon completion were not in my squad.

I think this is an ugly bug... and I feel cheated!