No worries, it’s no one’s fault, but thanks (all) for the help here!
I’ve been playing the household for a while now & eventually bought & placed the activity tables at different points in my gameplay. Fabricator first, then i earned the chemistry table via work promotion, shortly after i bought the robotics station - all are placed together in the basement. I tried moving the fabricator to ground level since I’ve been having other glitches happening regarding the basement, but the same result happens.
Nothing visible is path blocking the sims to the tables, i only have 2 wall hanging lights in the room & the stairs & doors are clear. I did recently get bust the dust kit & now have many dust piles all about tho. My sims can still path find to the tables. Half of the time they’re walking to the tables to do the action, start doing it, then stop. The other half of the time they don’t go to it at all & the actions go through to the sim & then just disappear once they get to it (the sim never does the “i can’t do it” shrug action).