If in-app purchases do not work for you, but you did everything right in Blueprint.
It’s your problem how do I solve it iOS Android app purchases.
You just need to change one value in Ue4 Ue5+
Adress for pc EpicGame Ue4.27 Ue.5+ Engine/Config/IOS/Engine.ini
In this file Engine.ini look for the line bUseStoreV2=true. and change to bUseStoreV2=false
you can do the same for android if it doesn’t work