MTO and non-MTO in GATP

Hi,

I have a sales order with a delivery block on for plant readiness. There are 2 order items in the SO, one MTO and one MTS. Now, when the gatp check is triggered for both these items together, it displays the ecc availability control screen. This should not happen. Instead, I would expect to see the apo availability screen for the non-mto item and nothing for the mto item since it is on delivery block.

Both these materials are gatp enabled.

Is this a normal behavior or is some setting missing?

Thanks,

Ram