I am having the same issue with a new application. the subscription options are empty. The screenshot that the apple reviewer attaches the ui picker is empty so no subscription options are being loaded. They are testing on an iPad 5 with iOS 13.3. I have tested on my iPad 5 and the options load correctly among other devices and simulators. On simulators for iPad sometimes they don't load with the decode object error. So you have to shut down xCode and restart then they load fine.
I have verified that my payment / tax / banking information is correct and they say status active. I even added an alert when the SKProductRequest failed, however the review didn't mention that so I am wondering if the SKProduct Request is NOT failing but just returning zero items.
Any suggestions are welcomed. I did request more information regarding the rejections so maybe they will give me more details.
Thanks.