I have just started my second attempt at building a prison, and this is the second time that the Staff room has the red flashing warning, telling me there are no prisoners assigned to eat at this canteen.
It is a staff room, so I would hope that prisoners arent assigned. Can anyone tell me if this is a bug? I will try upload a screenshot below.
No, save files can be loaded in any version of the game, they are even compatible across the non-steam version on the developers site and the steam version. Only the console and mobile versions, which have been developed by other companies are an exception to that.