'Not found' – original mod assets have disappeared from cloud

I'm a freelancer who works for Modiphius and created the the official mods for Fallout Wasteland Warfare (FWW) and The Elder Scrolls Miniatures Game mods.

We've hit a major technical issue with the FWW mod – ALL the graphics and other assets we uploaded to the Steam cloud (a couple of years ago) have disappeared.

After doing some investigations the following appears to be the issue:

This is the mod:https://steamcommunity.com/sharedfiles/filedetails/?id=2165945542

My local copy of the mod – obviously with local assets – is fine, but anyone trying to download the mod finds that all the graphics and odds etc are missing.

NB. I believe we only used assets we created rather than any third party assets which might have been broken.

What we've tried so far

  1. Checking paths to some graphics etc and comparing them in my copy of the mod with those in a user's broken version of the mod: Paths are correct/identical but when trying to view the assets directly I'm getting a 404 page with "Not found"

Eg.

The placemat graphic:http://cloud-3.steamusercontent.com/ugc/1044219423588489763/850C586860879A1CC14EEAC0466D6D7F410F3576/

A PDF:http://cloud-3.steamusercontent.com/ugc/1331327576941902363/77627990A70CAE374648A382FE3A5A315059671F/

2) Trying to upload all assets again to the cloud: This gives an error message that "No files need to be uploaded to the steam cloud".

3) Creating a copy of the mod and trying to upload assets: Same error message as above when uploading assets and copy of mod is missing assets as before.

It appears to be a Steam Cloud glitch – anyone know the best route to raise this?

Thanks

Al