nostr:npub18lmyh47aua400qaf230zlv7wsnvjr0nv3sz08hrvf7nnfnm7hqfq9599uz to confirm, are you using Damus iOS?

In the Damus DMs tab check:
1) requests tab - new DM requests sometimes appear here
2) check if your friends/WOT filter is on or off (top right DM tab)