Not receiving some photos in group messages
I have a group message thread with a mix of iOS and Android users. Some photos from one Android user appear as a gray bubble. Other iOS users in the thread can see the photos. This same Android user can send me photos outside the group thread (just to me) and I can see them with no problem.
I have restarted my iphone several times amongst trying the following things: quit and restart the messages app; reset network settings; made sure mms is turned on; signed out of apple id and signed back in.
I have NOT recently restored the phone - the photo doesn't appear from the time the message is sent - so this is NOT a case of "it was there and now it's not". iOS and all apps are up to date. I do not use iCloud.
Any suggestions??
iPhone SE (3rd generation)