Hi Fern — sorry about that. We have a known crash on the manual approval screen for iOS 17.4 specifically when the approval payload is over a certain size. Fix is shipping in version 4.18.0, currently in TestFlight, public release expected April 20.
Workarounds in the meantime: (1) approve from the web app at app.helix.io, which doesn't have this issue, or (2) install the TestFlight build if you'd like the fix sooner — DM me your Apple ID email if so.
For reference, the iOS app supports iOS 15+ so you're well within supported range; this is just a regression we caught late.