I wonder if she's ut too.
Could you post her routine?
Also, there's a big developmental leap at 18 mos and lots of LOs suddenly have trouble/ take longer settling at BT. A change in WD routine might help or you might just have to ride it out.
Wrt not going back in, I agree maybe not to keep giving back toys as is could become a bit of a game (we had that with my dd taking her sleeping bag off at 18 mos, it became a game until we stopped putting it back on if she took it off) for the LO, but def go back in if/ when LO is upset, to reassure them.