Signal messenger crashing on start

Xperia 10 III, SFOS 5.0.0.67, Signal 7.41.3
Background-Service is working, when I get a message, I can open Signal App by touch on notification. As long as I dont press the Back-Button, I can use Signal. If i press Back-Button Signal Gui closes. If it’s closed I cannot open it again.
I think in the 3ms, when the window opens, before it closes itself, I maybe see the ‘enter PIN’ dialog.
Opening from App-Chooser is not working.