I have this too. 

(I initially created a bug report for the robot janitors having the issue, but thought it got sorted so deleted it. But my guards are not installing theirs either. 

Have a screenshot of the guard with perk highlighted, it just never gets installed, and have a vid of the janitor; it's on their to-do list, but never gets done. 

My file won't attach (because of course), so here is the deleted link to my post that had the vid. I don't know if you'll be able to see it, you'll have to click to expand. 🤦‍♀️ Best I can do! 🤣

https://community.twopointcounty.com/two-point-studios/two-point-museum/bugs/1345-robo-janitor-security-guard-perks-not-installing?page=1)

I have this in a variation (not sure if you guys tried that) but they seem to be distracted by all their other tasks. 

For me some even started installing their perks but then they go do something else.

As a workaround I found that they do install them if you remove all the tasks from their task lists. They do install the perks if they have nothing else to do.

Yes, job assignments is what I mean. Couldn't think of the correct word.