Group message split into two chats on Mac
I have a long standing group chat with two others--one on an iPhone and one not. Today the chat split on iMessage on my Mac. My posts are appearing in one chat, the non-iphone posts are appearing in the other chat, and the 2nd iPhone user's posts come randomly into one or the other. The problem does not show up for either of them and fortunately does not show up on my phone. I have tried synching my messages, and deleting the second chat but the problem persists.
I have seen others posting about the same problem on reddit within the last few days. Some are guessing it is caused by the latest OS update (Sonoma 14.6.1), which is what I have. How do I fix this? It's quite problematic.