This is a very sudden issue and I have no clue why it's happening. I've been using a DataStore for a while now and have not received this error.
Can this be caused when you keep changing your DataStore's name?
My code has not even changed, this worked fine yesterday and now for absolutely no reason it's giving me this error? Does anyone know if this is on Roblox's side. The game is a group game and I am not the creator, but I never had an issue before. And the Enable Studio Access to API Services option is on too so I really don't know what the issue is.
if this question's answer is correct (and it may not be as it's from 10 months ago), datastores won't work in team create or group games of which you are not the owner of.
It should work in game servers, but I'm not sure why it only started for you now and if the above is actually correct.