This was fixed in Patch 1.55.105
When I press ctl-shift-c to enter a cheat my game gets dark and I can’t click on any Sims or objects. Therefore I can’t actually use the cheats.
Writing cheats still works normally.
I also can’t leave the mode.
A bug that came with Patch 1.54.120.
Enter the cheat you need, then Can the mode by hitting the ESC key (or pressing ctl-shift-c again). After that you can shift-click on any object again.