Can I ask you one more question?
Are you adding both switches to all of the groups like so?
I ask because a co-worker of mine is in the same boat as me trying to get virtual 3-way dimmers working with the reds and he read elsewhere in this forum to do “Master dimmer added to group 2 and group 4 of slave” and “Slave dimmer added to group 3 of master dimmer”. He says its working perfectly and he did not mess with param 12. I have yet to test this here. I suppose since he has no overlap he has no loop issue.
The thread in question is here:
3-way setup with two LZW31-SN dimmers in HA in endless loop - Sorting Category - Inovelli Community