Why `originalApplicationVersion` could be empty?

[wojciech-kulik]

I'm preparing to migrate a paid app to in-app-purchases. And first I started by checking the original application version and sending analytics events to see if I'm able to recognize the version correctly.

It worked in 99%, however, for 5-6 users it turns out that receiptInfo.originalApplicationVersion is empty. What could be the reason for that?