The ZMNHBD Flush 2 relay is running fine here with OH2 2.1.0.
The way I included it was with OH2 Habmin and not with the Gen5 Z-Stick Button.
Additionally, I didn’t link the “general Channels” - the ones first in the list for “compatibiltiy”, but only the “:switch_binary1” and “:switch_binary2” as well as their meter_watts. This works fine,
with the exception that when I used OH2 Paper GUI to change properties, I got the the group asscociations wrong in the json config, ie. the Error 404 discussed here.
Hope that helps anyone.