I have noticed this bug in 1.17.30. I just renewed on of my realms I have created months ago. When I went to the menu and wanted to add a certain pack into the game and when I tried to leave the menu, I would get a screen saying “Export in Progress” with the bar not going up or receiving “initializing upload” and getting sent back with a message “Some contents could not be applied.” I have tried to find ways for days, but couldn’t find a single way to go pass it. For example, I have tried replacing the world with the pack, and it would receive an error when trying to replace the world and it would work, but the certain pack would not be added while other packs did. It worked fine on a normal world but not on realms for some reason. Thank you for reading this and I would hope if this would be resolved.