This seems to be working here in (8.4.24037.15002, 2024-02-06) - but I have the popups set to open as buttons, not a menu - I actually don’t know how to set it to popup or flyout as menus.
I’ve enabled the “Cascade as menu” setting; Options → Toolbars → Sizes and Styles → ‘Cascade as menu’. I can also verify that the PopupToolbar operates correctly when this setting is turned off.
OK, confirmed. What’s funny is that the command is not run, but if you do a right click afterwards, it wants to run the command you just tried with the popup - so it is being registered as the last-used command, but not run.