Ok, just to make sure.
Wait about 5min and check all the variations of plots.
Make sure it isn't just one add-on or type of plot.
If it is still missing from everything -
Manually re-install the Sim Settlement mods and check.
Still, not there? Start rolling back your save.
I had glitch just like this a super long time ago. :mosking
In my case, my plaques went blank due to me uninstalling a user-interface mod after leaving the vault.
I did not catch this until much later in my game.
This was before I knew better.
That uninstalling mods in a running game is very bad.
It was my first bug report on the forums. I rolled all the way back like Tankthing and KG told me. My entire game was glitched right up to that very early point.
Find a point if you can where the plaques are working. Use MCM to spawn in the CityManaqger Tape if needed to test.
Good Luck!