It’s because they haven’t implemented the BDC messaging API and instead rely on the booking.com email address. If you send the guest a message and they reply, it works OK, but if the guest sends you a new message via the booking on BDC it doesn’t link together properly. This has been an issue for me for ages though, not just recently.

Hi Ryland, We worked on this again this morning and have been able to send a message successfully through to your guest Chad. We expect that this issue should be resolved going forward. You should be able to send messages from TV3 on any inquiries that were having this trouble before. There is no need to delete and re-import the booking anymore, but we need you to confirm to make sure. Setting up the exact scenario has been the major hold-up in getting this resolved. Thanks, Christian