gonzdevour My IAP has always said "Waiting for review" for me too, but it appears you (perhaps just updated this way) have to add them to the main app page in the new itunes connect UI. However, perhaps this is just requirement of the new system? I hope I wasn't rejected because the system changed while I was waiting for review...
Anyway I do the following:
On an upgrade button I have the following.
Is store available? => Fetch those products from store: "app"
Then I have the following to complete the process.
On product fetch complete => Purchase product "app"
On 'app' purchase completed => [Give them the full version]
On 'app' purchase failed=> [Show failed visual events]
Is product 'app' puchased? => [Give them the full version]
What about you?