Thats probably the reason, or at least part of it. On Windows I heavily modded it with tons of new items and sidequests, so that might have interfered with how it ran on Linux. However, I never installed any visual mods because I was playing the game on a toaster of a Windows PC and didn't want to risk lag. Its 7 years after the fact so its too late to troubleshoot, but I think it was probably a combination of the game not knowing what to do without my mods and WINE being weird.

My installation was also bit weird because I was new to Linux and didn't understand how things were supposed to work. I installed the Windows version of Steam through Play on Linux and installed everything through that client, rather than running individual games through POL. Then again, the installation option wasn't even available for the game on the Linux client so at the time I felt that the weird setup was the only way to play it