Meraki switches/clients offline after MX250 failover (NAT HA setup)

discussion topic at https://community.meraki.com/t5/Network-Wide/Switches-clients-offline-after-MX250-failover-NAT-HA-setup/m-p/11912#M292

 I have two MX250 firewalls set up in a NAT HA failover pair, using the network-connected design for VRRP heartbeats.

Both MX250s have one link connected to WAN1 in the same subnet and I'm using the Virtual-IP for client traffic headed to the internet.

The problems start when I disconnect MX250-Primary-Master's WAN1: the MX250-Spare takes over the master role within seconds. However most clients and switches do not regain internet connectivity- the switches go offline and clients connected to switches have no internet, BUT with the exception of the root switch MS225-24P-2K. The root switch regains internet connectivity and clients behind root switch can also access the internet. But rest of the switches and clients are offline- can not even ping the gateway (gateways are in the MX250). I have included two illustrations of the working setup and the nonworking setup after MX250 failover. I also have an open case with Meraki but no solution yet.