Had to get rid of Big Sur due to poor frame-rate and general issues. So replaced with High Sierra.
Bomes is still refusing to close normally when on the display, however when minimised, selecting [CLOSE] shuts it down without an issue.
As of Bome 1.9.0 pressing the X on Mac will hide Bome and not close it.
To close Bome MIDI Translator Pro use Cmd(Q). To just close the project use Cmd(W).
Many people complained the pressing X would close MT Pro when they were just attempting to minimize it.