I don't mean to doubt you, but are you sure that none of your 100+ subscribed channels have ever uploaded a short? Note that shorts aren't currently visible in NewPipe. You are of course correct that it could be caused by a different reason that is currently not known, though. If that's the case, it's usually a good idea to write a comment on the GitHub issue, but I understand that you might not want to do that.

I do think it's weird that this feature hasn't been added yet, though, as it seems pretty simple to implement. I'd write it myself, but NewPipe doesn't accept contributions for new features at the moment, which is kind of annoying.