Unable to see other's screen share

[OneWhoNeedsHelp]

I have a team in a certain region that is unable to see other's screen sharing when connected to their local office network. All they would see is 'XXX has started screen sharing'. However, they are able to see other's screen sharing while on their home network. Does anyone know what could cause this issue? If it's network, what should I be looking for? I would appreciate any help you can provide.