Okay, this is because you have 3 alt-activators enabled for plots. This causes a bug where all of them appear while in workshop mode and prevent you from using regular workshop functions on objects. I’m guessing you have:
Activate, Track Owner, View Plaque, and Options assigned to the four face buttons. Is that right?
To fix the problem, you need to disable at least 1 of these alt-activators.
You’re best bet is to open the Place Anywhere menu using the Place Anywhere aid item in your inventory. If you don’t have it for some reason, you can make one at the chemistry workbench.
Open the menu and change the Activation settings, so that the Place Anywhere button opens the menu rather than places objects.
Now, when you use the Place Anywhere button in workshop mode, it should open the Place Anywhere menu just like the aid item. From there you can disable/enable the “Options” alt-activator.
This will allow you to control when the alt-activators appear. Disabling “Options” will allow you to interact with the plots as normal, and then enabling it again will make all the alt-activators reappear. This is actually very useful, since it allows you to access useful functions without leaving workshop mode.
EDIT: Do not try to disable the Track Owner alt-activator using the Workshop Plus holotape. The option in bugged, will disable the wrong alt-activator, and cannot be undone.