I'm unlikely to find a solution from Steam so I'm going to ask here too.

I have a mod on the Workshop. I've updated it before. It's been awhile. I can't update it now.

I know how to properly package the mod for upload. The upload includes a .esp, .bsa, and .bsl

Total file size is 2.45 MB

The .bsa file contains meshes and sounds and is the main difference in the original file and the update I'm trying to upload.

Steam Cloud is enabled. I have refreshed my Steam files and validated the local files for both Skyrim and the Creation Kit.

When accessing the Creation Kit from another Steam account via Family Library Sharing

What I do and what happens >

Upload Active Plugin and Archive to Steam

Archive Data/ .bsa already exists. Use it?

Yes

Failed to get details on an uploaded preview image!

I found a .pub file for my mod, deleted it and tried again. Didn't get the error about the uploaded preview image but still none of my mod details loaded.

I get Failed to update the mod file on Steam! Error #2 this way. I'd love to publish this mod separately from the shared library Steam account. But neither the original nor the shared accounts are working.

When accessing the Creation Kit from the original Steam account (the original publisher as well) the only difference is I get Failed to update the mod file on Steam! Error #15

I've tried this on both a Windows 8 and a Windows 7 computer.

remove the preview image. select another one from your hdd (mostly even works if you re-select the same, but rather use a copy), retry

mostly works