Restoring In-App Purchase/Make and Read In-App Purchase do not work properly.
From what I can see neither of these have been reported as a bug which is a problem as they may not become resolved in the next test release.
Read In-App Purchase: Simply doesn’t work. Always returns Failed. The problem is within the engine code. Someone has already come up with a solution but it requires recompiling. LINK: [4.9.1] "Read In App Purchase Information" node don't work - Blueprint - Unreal Engine Forums
Restoring/Make In-App Purchase: Returns successful but always shows that there are no purchases made, even when making a purchase with “Is Consumed” unchecked. Not sure if related but here are some links: