I've had a couple weird ones with subs & red cards before but this different, and is the first time I did screen shots.
I went to make a substitution during a match and I was moving my players into position and it locked up as you see:
The match was a walkover, but Tlusty was in wrong position and suffered a bad rating; I wanted to pad out the goal difference with this weak team.
Also, later in the match a player got hurt and I was unable to sub him out.
Even after the match the glitch persisted:
Reloading the page resolved it, but given the time that takes on the machine I'm on it wouldn't have been fast enough to get back to the match.
Anybody else have this happen?