The current approval system for unposted purchase invoice is not usable as, even if you are not agree with the invoice, you have to post it and then ask for a credit memo. So it shoud be better to apply an approval workfklow on a posted purchase invoice which should blocked for payment (field "On hold" = YES) and then once approved, put this field blank so invoice can be paid
Category: Purchasing
Needs Votes
Ideas Administrator

Thank you for your feedback. Currently this is not in our roadmap; however, we are tracking it and if we get more feedback and votes, we may consider it in the future. Sincerely, Business Central Team