I am constantly getting the error in Unity IAP when I upload a webgl build on facebook.
Due to this issue the payment popup doesn’t shows up
My settings on the portal are correct, all the ids and other payment details as I have tested the InApp using FB.API call which is present in the Facebook SDK.
We have identified an initialization issue with the Facebook part of our plugin. We have a fix and it should be ready by the next version of the IAP plugin. (You should get an update notification in the Editor when this version is available.)
I apologize for any inconvenience this has caused.