RaspPi 4, “current” firmware as of 2/12/2020, Max2Play 2.51, standard Max2Play image without “apt upgrade”. 32-bit kernel, HDMI highres audio not enabled. Pretty much “fresh out of the box”.
When I attempt to set HDMI-Mode to “HDMI” and click “Save”, HDMI-Mode will be set to “DVI/VGA”. Setting it to “DVI/VGA” does the same, this is not a case of the two options simply being switched when saving.
Happily, HDMI output works with HDMI-Mode “not set (default)”.