This has always happened with my sims. I have to make them stand up before they will teleport. I've never had them float though; the teleport command just simply won't work if they are sitting or laying down. I have to go to where they are sitting, click the floor/ground in front of them and tell them "go here". They get up so I go back to where I want them and shift click and use teleport and they do.
Crin is right though; using cheats is not supported. I did not add a "Me Too" as my sims don't float because of this nor have I ever had to reset them.
