Has anyone else had an issue with VRRP flapping between routers when it is connected to a bridge with an MLAG to other switches?

I've got 2 CCR2216 setup with a VRRP connection.
The 2 100G ports are utilized in a LACP to connect the 2 routers. They have their untagged VLAN set to 10 and also pass VLAN 1 tagged.
I then have 2 ports from each router going to 4 ports on a switch. Duplicate that 2 more times for a total of 3 switches connected.
All of these pass VLAN1 untagged.

I swapped the configuration so that instead of an MLAG, I have 2 LAGs on each switch, and utilize RSTP. Now the VRRP doesn't seem to flap back and forth.

I'm running on 7.13.3.

Can this be a coincidence that the issue went away?