Bedrock 1.19.10 - Chat in realm not working

Hi Minecraft team,

My brother and I share a 2-person Bedrock realm, and unfortunately there seems to be an issue with the chat on the realm. I'm the owner of the realm, and my brother has an Admin role in it

I can chat normally without any issue and my brother can receive it.

However, my brother's chat doesn't work. When he sends a normal chat message via T, I won't receive it at all. When he uses /say, it will instead return with a bunch of hashtags (########). Only /tell and /whisper appear to work, though you can imagine that being annoying to use all the time. For some reason, I also see his whispers twice.

I've already tried reinstalling the game and checking my Microsoft account's security & privacy settings - they're all enabled correctly. He equally has done this. 

Any ideas on how to fix this? Any additional info required?

Thanks in advance