iOS Group Messaging with iMessage bug

I'm running into the same issue, at first my Mac was showing iMessage and my phone was showing SMS, now both are showing as SMS. However I have a smaller group (only 4 people including me) and it still shows as iMessage on both phone and Mac

**Edit for Clarity**

Have a large group with 17 people, and a smaller group with only 4 including me, Smaller group is okay, bigger group is the one with the issue.

Confirmed with someone in the groups who also updated that they see the same thing,

Seeing this on my end too. One of the guys in my group chat is international and I think changed their account, but on my Mac I'm still able to chat with it as an iMessage chat, but on my phone it's registering as a text message chat. It's so bizarre for me as I can't figure out why it's reading it differently all of a sudden.

I read that this issue can occur when there is an „too old“ Apple device logged into iMessage. Then the sms and iMessage fusion in one chat causes errors and you are stuck with sms. Even after I removed all older devices and logged out of iMessage on other devices, the error persists.

In my case a group of 8 does not work with iMessage, although I can send an iMessage to each one individually. Maximum annoyance. Especially because have the people receive a sms in our privat bilateral chat when I write into the group chat. However, all those with international number won’t receive anything because those messages would cost and I don’t have money loaded onto the account.

Please Apple, fix this mess.

I was able to fix this issue. In my case, one of the phones in my group chat was turned off. Check to see that everyone’s phone is on. Also, I manually shared the verification code with them.