trouble with uplink between vlan'd switches

hi,

i'm sure i'm just missing something in my logic... but what? lol.

i have two switches with the same configuration (basically i've segrated each switch into two switches)

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switch A

default vlan 1 untagged on ports 1-12 and excluded from ports 13-24

"voip" vlan 212 excluded on ports 1-12 and untagged on ports 13-24

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switch B

default vlan 1 untagged on ports 1-12 and excluded from ports 13-24

"voip" vlan 212 excluded on ports 1-12 and untagged on ports 13-24

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switch B is uplinked to switch A on ports 1 (for vlan 1) and 13 (for vlan 212)

vlan 1 communicates fine. dhcp works across both switches.

vlan 212 doesn't communicate across the switches.

if i take out the uplinks... and instead uplink vlan 212 on switch to vlan 1 on the other switch... they those two vlans communicate.

what am i missing?

switches are ubiquiti edgeswitches.

thanks