It works for me. You just have to have the collection that you want to expand or collapse highlighted. For example, pick and highlight the drawing name in the toolspace and type * (or +) and all styles expand. Type - and they all collapse. As noted you have to use the number pad.
*edit* I just noticed + works a little different than *. One thing I don't like is - hides all the collections below the drawing level. I'd rather see the collections but have them all collapsed.
Jeff Paulsen
Civil 3D 2020.4 | Win 10 Pro N 64-bit
Xeon W-2223 @ 3.60GHz, 32GB Ram | NVidia Quadro P2200