This is an untested idea. You can try it but I take no responsibility for what may happen.

Exit Steam
In the Workshop folder (..\Steam\steamapps\workshop) there is a file: appworkshop_365960.acf
Very important, make a backup of the file first. Untested idea remember.
Open file with Notepad.
There should be two "1428803438" entries (4 or 5 lines of text per entry) in the file you want to delete.
Be careful you don't leave an empty line or other formatting errors.
When the two entries are removed, save the file and start Steam and rF2.

The main reason I'm not too confident in this working is because you'll notice there is a "SizeOnDisk" value and probably other values that might cause errors.

If that doesn't work you may have to unsubscribe from everything and then delete everything 365960 in the Steam folder relating to the workshop.

ooo . . . risky . . . & I ain't all that frisky
'cause, quite frankly, the damn thing up & disappeared from my hdd. who'd of thot that !! the magic of technology.

Good to hear it sorted itself out without you having to try my stupid idea.

Although not quite the same problem you had, this post has a good thing to look for with workshop problems.
https://steamhost.cn/steamcommunity_com/app/365960/discussions/0/3247565033766352542/#c3247565033772314725