If I trigger 'Show Desktop', click on the desktop and cancel the show desktop with 'Mission Control' action then the next time 'Show Desktop' is triggered I get 'Mission Control' instead. This state persists until activating a window (moving focus away from the desktop). If 'Show Desktop' is cancelled with another 'Show Desktop' then everything works fine!
This doesn't occur with the standard Apple controls (trackpad gesture or touchbar buttons). However, within BTT it doesn't seem to matter how the actions are triggered, I have tested with MBP trackpad (both Named Trigger and directly assigned action) and mouse buttons (JS implemented long/short clicks).
16" 2019 MBP