DM on Nostr is unreliable and basically broken, so YMMV.

You are probably missing a relay supporting private DMs Try adding, wss://auth.nostr1.com/

invisible ink... 🤔🖊️

Same

dms are broken on nostr because some apps like Damus and Primal are using outdated legacy DMs while many other app are using more modern DMs with more privacy. check out 0xchat for DMs. it's a nostr app dedicated for DMs.