I am not so sure, because it happened to me a couple of times, too. I suspect a bug in Discourse, but was never sure, if it was not me clicking “wrong”. When I deleted a post and replied again, it appeared to work fine (but I do not remember, if “most of the time” or “all the time”).
Anyway, yes I installed it from OpenRepos (it was before installed from chum).
Thank you very much, especially as you ran an explicit test!