PROOF FOUND
It was already pointed out in other topics that your first day league arrangement is done before the 3rd day, and you could see the first match after you complete the 2nd day cup match
Indeed if you try to move the first Champions League match, that is on Tuesday 07 March, you finish in some black zones and you can't move the game there
But I have seen that the same thing happens for the last CL group match, on Friday 17 March. Indeed, I have the match at 06:59 am (GMT + 1) and if I try to move it I see two big black zones
One is between 09:24 and 15:22 so there is a league match at 12:22-12:24, for me or my opponent
One is between 16:03 and 22:01 so there is a league match at 19:01-19:03, for me or my opponent