Like the author of GRASS not working with QGIS 3.6, I am unable to use Grass plugins, with the error:
This algorithm cannot be run :-( The specified GRASS 7 folder "C:\OSGEO4~1\bin\bin" does not contain a valid set of GRASS 7 modules. Please, go to the Processing settings dialog, and check that the GRASS 7 folder is correctly configured
This applies whether or not I start QGIS using the "QGIS Desktop 3.6.3 with GRASS 7.6.1" option or not.
I do not have an option to specify the GRASS path in the Settings > Option > Processing menu.