Same issue here!
Have owned Sins in a number of iterations over the years, and have never had a problem like this! I've played this game on some serious potatoes, small laptops, etc, so to say that I am disappointed that it doesn't work on this system is a bit of an understatement:
Operating System: Windows 10 Home 64-bit
AMD Ryzen 7 3700X
Matisse 7nm Technology
16.0GB Dual-Channel Unknown (20-19-19-47)
Alienware 0NWN7M (AM4) 26 °C
8176MB ATI AMD Radeon RX 5700 XT (Dell)Operating System
When I try to play Sins: Rebellion, the launcher page/window shows up, I hit "play" (yes, have validated all game files) then there is just the dreaded circle infinitely going around and around (used to be the hourglass, remember? lol)
At that point, all I can do is a restart via the Task Manager Blue Screen or a hard power down.
Already cleared the Steam download cache and even re-downloaded the game.