For information, if you want to reschedule sale orders in bulk, then only, you need to execute V_V2, as it will affect system performance. From your post, it could be observed, you were trying to allocate stock only to two orders in which case, you can very well do availability check individually. Try individually and update here. Also have you tried to uncheck the "Fixed date and quantity" and ran V_V2 ?
G. Lakshmipathi