FYI, using the Query Multiple Taxonomies plugin, taxonomies created with this plugin are appearing in the back-end widget congifuration, but do not appear in the multiple-taxonomy drop-down widget menus.
However, standard post categories and tags are.
I've tried a number of Types taxonomy configuration options, with no luck.
Currently, each one is public, hierarchical, and all other defaults are true.
Any suggestions for trouble-shooting to find out why the Types custom taxonomies aren't being displayed?