When using purchase lead times with checkbox 'working days' marked the Old master planning uses the vendor calendar as highest priority to use working days. With planning optimization this working day is ignored and only coverage group calendar is used.

This is was reported under Issue 880668 and marked as designed.

From functional perspective functionality has been lost as it is not possible anymore to use different working days by vendor. Only applicable for the item itself.

Solution implement working days by vendor again as used in 'old' master planning