Players not being able to spawn SENTS until re-installing

Hi there, as the title states, some of my players (seems random, happened to me twice in 5 days) cannot spawn entities through the F4 Menu. It doesn't matter which entity, none spawn. The only console output / log I get is that the player used the /<entityname> command, but not that it was spawned.

To get it working again, users have to reinstall their gmod, which seems unreasonable.

Since I haven't found anything regarding this specific issue, I'm just gonna ask here.

Do any of you know what the issue could be?

We're running DarkRP with a lot of addons, but everything updated. Also, we're using x64 server branch.