Hi @wazza_d
To give an update, based on the video you provided the initial change from the assistant manager is intentional behaviour. As the custom schedules are with Saturday as Match Day, so when there's a game on Sunday instead, the recovery sessions move to Monday.
However, there does seem to be an issue after you make further changes to the new schedule, it's getting reset for some reason. This is something we can look into further but won't be able to make any changes to in this FM cycle.