Huawei P10 SMS/MMS issue

I picked up a Huawei P10 and it's great so far. My one issue is with text messages. Some group messages were received incorrectly (they were marked as only sent to me even though they're MMS) and Facebook Messenger is unable to reliably see the SMS/MMS messages on my phone. Basically, new SMS/MMS will appear on FB Messenger and disappear shortly afterwards, never to be viewable from the app again even though the messages are stored on the phone. I called AT&T and they said everything looks fine on their side and there's not much they can do since this is an unsupported, unlocked phone. Anyone else have these issues?