ES-16-150 STP to ERX Switch breakage

Was setting up to do some testing with the ES L3 capabilities.  Plugged an ES-16-150 into an ER-X that I am using as a switch and it broke switching.  ER-X is on 1.8.5.  ES-16 is on 1.5

ES-16-150 was just factory wiped.  Had only console cable and network cable to ERX in port 0/16.

ER-X has very basic, vlan-aware switch setup.

 switch switch0 {
     mtu 1500
     switch-port {
         interface eth0 {
             vlan {
                 vid 10
                 vid 250
             }
         }
         interface eth1 {
             vlan {
                 pvid 10
             }
         }
         interface eth2 {
             vlan {
                 pvid 10
             }
         }
         interface eth3 {
             vlan {
                 pvid 10
             }
         }
         interface eth4 {
             vlan {
                 pvid 10
             }
         }
         vlan-aware enable
     }
     vif 10 {
        address 192.0.2.3/24
	address 2001:db8:0:2::3/64

A few seconds after plugging the ES-16 into the ER-X, the ER-X stops all switching.  I was still able to connect to the device itself.

By setting "no spanning-tree port mode" on 0/16, the ER-X started switching again.  

Anyone else able to reproduce this bug?