Didn’t work for me either.
Neither did I get the all-clear followup message.
That feels particularly bad, because one of the main reasons that we got cell broadcast is exactly to warn people like us who can’t have the apps.
I hope that this is ever fixable and that it’s not a baseband firmware issue.
(Is the BM818 firmware even proprietary? There seems to be a thread about it but I don’t understand whether they’re talking about a replacement firmware or the original thing.)