Unity IAP still causes Windows Store 8.1 to fail WACK

I namely wanted to reply to this thread:
https://forum.unity.com/threads/solved-does-unity-iap-still-support-windows-8-1.499481/
and report that the issue is still present as of March 6th, 2018. The thread is locked, for some reason??

Basically i'm trying to make a 8.1 build of my app for Windows 8.1 users, and managed to get everything done except that it now fails WACK because of unsupported API use in Stores.dll

I'm using Unity IAP 1.17.0 with Unity 5.6.4f1

Paging @JeffDUnity3D

 

Our support for Windows 8.1 is limited.

 

Uhm... well, I think you mean you don't support Windows 8.1 :|
This isn't something minor, this is something that literally prevents a Unity built app from passing cert and being on the store.