Apparently the GitHub was the wrong place (sorry!) so I am opening a message here.
To save repeating myself, here is a link to the issue I posted: https://github.com/Facepunch/garrysmod-issues/issues/2436
Does anyone have any ideas? I initially thought it could be a bug due to it happening on a fresh install, hence the issue - but I would love to be proven wrong or if there are any solutions.