Unable to add IPSec Interface to Zone

Hello,

i've configure our FortiGate Systems with FortiManager. In the past i've configure a Zone with one local Interface (WAN2) to connect the FortiGate to our MPLS Network. Now i've configured a IPSec VPN Interface Tunnel and would like to add the IPSec Interface to the Zone which inherit the local Interface WAN2.

But when i'm install the Policy my FortiManager drops the Zone-Configuration i made under Object Configuration.

The IPSec VPN Interface use as local Interface "wan1" (because Internet breakout).

Regards