Items staying persistent [problem]

Hello,

I bought Gmod a few weeks ago, but I’m having a problem when I make items persisent. For example walls, floors, ceilings etc.

After I made the items persistent and save the game, either by Q > Saves > Save or via the console > gm_save, the items will not be persistant anymore.
I can freely move them with the physics gun again. This is pretty annoying because it messes up doors and other contraptions.

I already tried disabling and enabling all my addons. I have addons like the stacker tool, key-pad for doors, a few NPC models etc. Nothing really special imo.

Any idea on how I can solve this problem? If you need to know more about my settings, OS etc. feel free to ask.

-RobertInc