Just a comment here. The newest release of Photoshop 21.0.1 running under Win 10 build 18362 had an issue with the selection box module. I could run one choice but when I tried to run a second there was a pop-up window stating it could not finish the command (loading) due to a module error. Or words to that effect. The modules would load from the PS menu Filter > NIK Collection> drop down but the Tools in the Selection box could not be used.
I reinstalled (did not remove, yet) NIK but had an issue with the install due to the updated DxO PhotoLab 2.0. The NIK box was not running when I retested Photoshop due to the call out during reinstall. I ended up uninstalling both Nik and PhotoLab, restarting the system and reinstalling. As of now, all selection box tools are working as expected. Plus DxO photolab has been updated as well.