I see the same, using yakihonne & Amethyst on Android.
I can send from yaki and it is received in Amethyst.
Sending from Amethyst does not show in yaki, but they are sent to the DM relay.
In Amethyst I can see all messages on both accounts.
nostr:npub1zafcms4xya5ap9zr7xxr0jlrtrattwlesytn2s42030lzu0dwlzqpd26k5 I tried DMing someone on Amethyst with Yakihonne while secure messaging was enabled (NIP-17). They were able to see my messages but I was not able to see theirs. Could be a nostrability issue. Yakihonne 1.8.5 (10) TestFlight on iOS 18.7
Discussion
Thanks for the feedback Ryan we wil check it out soon 🙏