Pool member on standby LTM were Online without VLAN was trunked to upstream switch

Hi,

I have an F5 pair in Active/Standby configuration. I am running version 13.1.1 and both devices are in Sync. The LTMs are configured in one arm mode. The problem is initially Standby LTM was showing all pool as online without the standby device VLAN being trunked to the upstream switch. After I disable/enabled the pool member on standby LTM, all nodes becomes offline.

Not sure why the nodes were showing online without the application VLAN not trunked to the upstream switch???. Any help will be appreciated.