After uploading a build to the alpha release channel, creating a test user, and downloading the build from the Oculus app, I am then able to create new builds locally, and use IAP successfully.
My colleague has gone through all the same steps. When they run the build which they downloaded from the Oculus app, they can use IAP successfully. But when they run a newly created build locally, IAP does not work. I made a build locally, and was able to run it and use IAP; but when my colleague ran the same build, IAP failed.
We have both followed the steps at https://developer.oculus.com/documentation/platform/latest/concepts/dg-iap/.
I download the build from the Oculus app I run the build, and I am able to use IAP successfully I make a new build in Unity I run my new build, and I am able to use IAP
My colleague downloads the build from the Oculus app My colleague runs the build, and is able to use IAP successfully My colleague makes a new build in Unity My colleague runs their new build, but Platform initialisation fails, and they are not able to use IAP