In Apple's recent update to its developer tools, 32-bit support has been turned off by default and supporting older devices has become an increasingly difficult, time consuming process. It's no longer feasible to support both newer hardware (e.g. iPhone X) and older versions of iOS at the same time without a significant amount of development work.
Recently, we've had to pull changes that were introduced to support iPhone X optimizations (in v3.3) as the app came to a grinding halt on iOS 9 & 10 (crashes at launch). After a few sleepless nights, it has been discovered to be due to a (somewhat) known bug in how Apple re-compiles bitcode enabled apps on their servers. The amount of re-work and re-engineering required to support older hardware (and iOS versions) is simply no longer worth the time and costs involved.
We've therefore decided to end support for older devices (and by extension older versions of iOS, namely 9 & 10). v3.3.1 has been marked as the final release that will support iOS 9 & 10. iOS 11 has been out for some time now and we're a few months away for iOS 12 to come out.
The next update (v3.3.2) will restore support for iPhone X along with other iOS 11 optimizations. If you're an iPhone X owner, skip v3.3.1 if you like and wait for the next update to arrive.