well, that explains it
Hello, R. Tumblr is no longer supporting tags with hyphens. This change has been made to ensure consistency in tags and tag searches.
We are aware that this change is breaking tag filter links in some cases. You may have to remove hyphens from your tags in order for your tag filter links to work.
Having looked a little more closely, I see why—hyphens (technically, hyphen-minuses) have suddenly become the substitute character for spaces in tags. (edit: Plus signs don’t work anymore either. I wonder if underscores were broken too.)
advance notification sure would have been nice and a mass tag editor would be even nicer, but I guess redundant messaging systems and Missing E fearmongering takes priority over stuff like that huh
