Assembly Definitions:The type or namespace name 'InputSystem' does not exist...

Unity Engine
1

Ok I’m getting lost here… trying to ‘organize’ my code using Assembly definitions, but I can’t get dependencies to work. For example:
I’ve got some GameLoop manager that I’d like to provide with some input actions from the InputSystem.
So to the Assembly Definition I add:

Above the script itself I add:

using UnityEngine.InputSystem;

Visual Studio is fine with this; no errors, and I get access to all InputSystem code.
Unity, however, throws this at me:

1229×51 13.5 KB

(The “type or namespace missing” error we’ve all seen come by).

I don’t get it… what am I missing here? I tried regenerating project files from the Preferences, restarting Unity, nothing… Please don’t tell me this is where I have to manually delete a bunch of files to force a rebuilding of some library o_o

2

Ok so I deleted the assembly and created a new one with the exact same settings and the error is gone… Which works for now, since I’ve only have a few assemblies (and nothing depended on this one yet), but this is of course no solution. Anyone knows the proper way to deal with this? Or what causes this to begin with?