Steam Workshop Addons - addon header invalid

So, I have installed some addons via the Steam Workshop. However, some of them are not showing up and they are redownloading every time I open gmod. If I open the console, I can see the following error messages:


Addons have changes - remounting
Not loading addon 'addons/improved_rideable_heavy_127951915.gma' - addon header invalid
Couldn't mount addon [Improved Rideable He][addons/improved_rideable_heavy_127951915.gma]
Removing bad addon addons/improved_rideable_heavy_127951915.gma
Not loading addon 'addons/rideable_flying_heavy_(work_in_progress)_222714387.gma' - addon header invalid
Couldn't mount addon [Rideable flying Heav][addons/rideable_flying_heavy_(work_in_progress)_222714387.gma]
Removing bad addon addons/rideable_flying_heavy_(work_in_progress)_222714387.gma
Not loading addon 'addons/fly-able_heavy__265217535.gma' - addon header invalid
Couldn't mount addon [fly-able heavy!][addons/fly-able_heavy__265217535.gma]
Removing bad addon addons/fly-able_heavy__265217535.gma
Not loading addon 'addons/working_tardis_217367303.gma' - addon header invalid
Couldn't mount addon [Working TARDIS][addons/working_tardis_217367303.gma]
Removing bad addon addons/working_tardis_217367303.gma


This is only for a few mods, and for the same ones every time.

Can somebody shed some light on how to fix this? (I’ve already tried deleting the .gma files in case you were wondering)

Thanks…

…hello?

You can’t subscribe to saves, dupes or demos.

…actually that makes sense.

Is there, then, a way that I could search for a dupe in-game so that I can save it?

In the “Dupes” menu?