There are numerous reasons for it to get stuck on the “Loading” screen, as described in many threads (Stuck in Loading Screen after Update). And the fact is, you aren’t actually stuck on the loading screen, you are just seeing the GameShells default background which just happens to be an image that says “Loading”. There is an open ticket to fix this (https://github.com/clockworkpi/launcher/issues/181).
But from the looks of it, you are actually just experiencing this issue (https://github.com/clockworkpi/launcher/issues/180), which has been fixed, so you probably just need to update your launcher.
Essentially before the fix above, the launcher would initialize 72 different font objects as well as some other things every time the the launcher starts (i.e. every time you start and exit an application), creating tons of handles to the files and after several times, the launcher crashes, leaving you on the “Loading” screen.