EDIT - answered
nevermind, figured it out. i have "use the same grid division in main and MIDI editor" checked, and the main screen overrides the midi editor. i re-assigned the shortcut to the main screen swing command and it works now.
this should probably work both ways so rubes like me don't get suckered
what's happening here? my swing display is missing. it looks like the UI struggles to show it, but it's overwritten. i get flickering while adjusting this param for the first time after opening a ME, and just this bracket afterwards:
midi editor settings are as follows: