Photos show up as grey boxes and never load in my chats

Grey boxes are almost always a cache or storage problem. Clear the app cache, and check you actually have free space on the phone, images fail silently to load when storage is nearly full. A restart after clearing usually brings them back.

If all else fails, log out and back in, it refreshes a surprising amount.

Can vouch for the airplane mode trick, works every time for me.

Restarting the phone entirely did it for me when nothing else worked.

The answers here saved me a support ticket, thank you.

Solved the same thing by switching between wifi and mobile data, oddly enough.

Restarting the phone entirely did it for me when nothing else worked.

If clearing cache does not do it, it can be a network filter, some office and school wifi block the image CDN. Try the same chat on mobile data and see if the pictures load.