I use NIP-17 DMs daily in multiple clients (Amethyst, 0xChat, and Chachi) and work pretty well. Sounds like a client issue.
Discussion
Always a client support issue 😔
Kind of a UX nightmare tbh.
Yes, if you use a client that does not support proper DMs you'll have terrible UX. I highly recommend 0xChat for that, it's available in every platform and is the most advanced nostr chat/dm app.
Are you supposed to periodically open it to see if people dmed you?