Subscription iAP Fail Reason unknown or -1001 on iOS

Hello, we are having an issue and can not find any solution about it, Apple keeps rejecting us due to this problem. We have 3 non-renewable subscription IAP products and when you tap them to buy, it tries to buy then after some time it returns as logged below. Any solutions? Some guys say its an Apple Sandbox Environment bug but Apple does not get it and keeps rejecting.

2018-03-21 17:47:54.174975+0300 xxx[23876:7332591] UnityIAP:UpdatedTransactions
2018-03-21 17:47:54.175265+0300 xxx[23876:7332591] UnityIAPurchaseFailed: -1001
onPurchaseFailedEvent({0}): com.xxx.xxx.vip_package_10
UnityEngine.Purchasing.PurchasingManager:OnPurchaseFailed(PurchaseFailureDescription)
UnityEngine.Purchasing.JSONStore:OnPurchaseFailed(PurchaseFailureDescription, String)
UnityEngine.Purchasing.Extension.UnityUtil:Update()

(Filename: /Users/builduser/buildslave/unity/build/artifacts/generated/common/runtime/DebugBindings.gen.cpp Line: 51)

OnPurchaseFailed: FAIL. Product: 'com.xxx.xxx.vip_package_10', PurchaseFailureReason: Unknown
ShopManager:OnPurchaseFailed(Product, PurchaseFailureReason)
UnityEngine.Purchasing.JSONStore:OnPurchaseFailed(PurchaseFailureDescription, String)
UnityEngine.Purchasing.Extension.UnityUtil:Update()

(Filename: /Users/builduser/buildslave/unity/build/artifacts/generated/common/runtime/DebugBindings.gen.cpp Line: 51)

 

It was working on TestFlight version then stopped working on TestFlight after a day and thats why failed on AppStore Review.

I could reproduce it yesterday but now its working, I told the person at Apple review thats its an issue Apple related but he/she said they cant assist technical support for it and it has to work as desired. Later I read some discussions about that problem that it sometimes work and sometimes not and there is way to trigger fixing by adding a new IAP product on itunesconnect just to refresh product list or smt like that, now its working and I am praying will keep still working till it passes review. Btw I do not only get "-1001", sometimes I get "-1005" and sometimes "0". Thank you for your support, I will just keep waiting till review and will share the result.

 

It fixes the problem If I add a new product on itunesconnect side and started working, this is probably an Apple bug.