[Debug] Breakpoints completely misbehaving. HELP!

I'm trying to debug some code, but for whatever reason the breakpoints and debugging is misbehaving in a way I can't comprehend.

In the image, the "breakpoint" is hit, but it highlights the wrong line and according to the stack trace it's in a completely different class than the highlighted line.

The code is in a .dll of an in-office created framework solution that's copied into the Unity project.
I made sure the .dll and the .pdb files are up to date, but it keeps showing the above behavior.
It's making it very hard for me to debug certain functionalities.

I've tried a lot of things, I tried fixing the Visual Studio Tools for Unity, rebuilding the solutions, nothing has worked so far.

Also, every time Unity rebuilds the assets after I compile the solutions, it throws the following exception:

I can't explain this either, I'm not sure if it's related and I haven't been able to find any useful information about it...

I really hope someone can help me.

 

Bump!