@nocturne bloom There is an on-going bug affecting PC only where the Casino Heist will kick players after reaching the mantrap tunnel.
You can prevent yourself from being kicked by going to Settings > Graphics then set VSync to Half and enable 60Hz refresh rate. This will enable a 30fps cap which prevents the bug from happening.
Note: All players must use the following graphics settings to cap their fps to 30
You can also use apps like RTSS (RivaTuner Statistics Server) to setup a hotkey to cap GTA5.exe to 30fps.
Alternatively, the bug seems less likely to happen when there are more than 2 players in the heist.
Requested by: @wheat basalt