I went back to a game that I played before Ambitions came out and they have like 13 gnomes and of course, now they don't move. I had read, if you kick them and stand them back up, they will move again. Wrong, lol.
I too had gnomes that did not move from a pre-Ambitions game. I tried putting them in my inventory, tried moving them to a different place on the lot, tried kicking them and tried standing them up. Finally I just gave up and placed them in the corners of the garden to act like sentries.
I then acquired several new gnomes from Ambitions that moved all over the place. One day, after several sim weeks went by, I noticed that two of my pre-Ambitions gnomes were missing from the corners. I paused the game and went looking for them. Finally found one of them deep in the basement and another under a flame fruit plant. For some reason they started moving again.
Don't know if the new gnomes told them what to do or ??