That’s what I had assumed. Apparently, for some reason I don’t understand, my notebook ended up with an ancient version of PlutoUI that didn’t have that function.
It appears details was added in v0.7.56 in Feb 2024 (not sure how you already had it in 2021 
)
It doesn’t help that details isn’t mentioned in the PlutoUI documentation! In any case, it’s working now. Thanks!