Anyone else unable to update their iOS Threema?

A new update is advertised on the Apple apps store. But when I try to install it says I can't because the app was bought by a different user or refunded or cancelled.
But quite the opposite is true. I even bought copies as gifts for friends who I wanted to stay in touch with.
Anyone else having the same problem?

Problem semi-solved... During a support call with Apple some time back Apple "refunded" me for Threema against my will. Unfortunately this means I have to buy Threema again to get the updates, and worse still deinstall Threema first so that I can buy it again.

The bottom line is I probably lose all contacts and conversations in the process so I'll stick to using the old un-updatable version.