We used to have a tag for #apps, and I removed it (because we don’t have an “apps” team, and also because it is too grab-baggy to be a very useful tag). But, somehow this got entangled with the workstation tag — it was set as an alias, but something was confused internally so while you couldn’t select it, spammers hitting the site via the API were creating posts with #apps, which wouldn’t show up except got listed under workstation. I thought I had straightened this out and everything was fine, but somehow sometime after I did that, the workstation tag itself disappeared, leaving posts with no tags.
Project Discussion doesn’t allow untagged posts, so I fixed this by creating a “new” workstation tag and adding it to all untagged posts — there didn’t seem to be any others. This may have missed some that were supposed to be tagged with multiple things (e.g. also silverblue), but… I don’t think anything too important. So it should all be fixed now, and this post is just a FYI for anyone wondering what happened.
I’m asking Discourse support to investigate and make sure there’s nothing else similarly wrong.