Has this always been the case with this game? Or it was okay up to some point?
Does it happen with every prison, or just one or some particular ones?
Any mods in use?
Please attach here the game log C:\Users\{UserName}\AppData\Local\Introversion\Prison Architect\debug.txt
To see the AppData folder you'll need to enable View Hidden Items in File Explorer.
AND DXDIAG is a program you run from the Windows search box on the task bar. After running it will open a window and start collecting info with a progress bar in the lower-left corner. When it completes click the 'save all information' button and save it to a file then attach that file here.