flowing to the invoice if the SO Date and Billing Date is the same
Do you mean to say sale order is nothing but "Created On" date? Nevertheless, it should not happen.
Sales Org/Customer/Region/Delivering Plant
Are you using the same combination for the old one and new one with different validity period?
in which case the basic price ZINV where condition category is H is absent in the invoice.
You have to explain whether the discount condition type is not flowing or selling price itself is not flowing. Also, it would be better, if you share the screen shot of your pricing procedure and condition tabs of sale order and billing
G. Lakshmipathi