incoming call notification doesn't work if phone is in vibrate mode

with my phone on ringing mode, an incoming call triggers both a single default notification sound, a single vibration, and the extended call ringtone sound. vibration does not continue while the phone is ringing. these aren't ideal, but at least the default phone ringtone is used and I'm alerted to the call while it's ringing.

if the phone is set to vibrate mode, the call notification pops up on screen, but never vibrates, despite having "vibrate" set in the settings for call notifications. as my phone is usually in vibrate mode, this means I miss all calls unless I'm looking at my phone at the time.

I've experienced this on both my phone (unihertz jelly 2) and my wife's pixel 4a, app v1.0.13.