problems with entering simul

When I try to start simul with number of people It is difficult to collect them all: some people are dissapearing from the list after I accept them. For example player from iphone while waiting I accept all people doesnt touch anything, his phone's display switchs off and he is dissapearing from the list! why?? I thing it is problem of last month, i cant remember things like this in summer.
It is not right.
And
May be make possibility to enter simuls after the beginning?

There is some automatic system to remove offline players from accepted simul players. (So that you don't start a simul with 10 players and only 5 are online).

The phone example is interesting. Perhaps there should be some tweaking done here, not sure.

This happens to me too. I can't seem to find a way of flagging this to Lichess.