Starkey notifications issue with iPhone(s)

I recently tried Starkey Genesis AI hearing aids and they have been changed, very recently, for Starkey Edge AI, again ITCs.

Unfortunately, the connection with my iPhone (SE 2022) is still somewhat poor.

The phone call notifications work correctly, but not other app notifications (e.g. Mail, Messages).

The notification sounds range from silent (with some vibration) to around possibly 40% of full volume.

In Settings, Notifications, when I click on the existing notification, it varies from silent to vibration or possibly 25-40% (in my estimation).

Yet, if I go click on the same notification again, it is at full volume.

However, if I click elsewhere and then return to that same notification and click it again, it again only sounds from silent to 25-40%.

I use a ringtone for my call notifications, but Sounds for the other notifications and I wondered if that difference was the problem or at least part of it.

To that end, I’ve downloaded 4 ringtones (at £0.79 each!). The notifications seem to be working correctly using downloaded ringtones only, so I’ll see what happens for the next few days …!

I have checked my iPhone with an Apple Genius, who couldn’t suggest anything else I could or should change, other resetting my phone and trying another iPhone, both of which I have done, with no changes.

My iPhone settings are:

Settings, Accessibility, Hearing Devices
Play Ringtones - On

Audio Routing

Call Audio - Always hearing devices

Media Audio - Always hearing devices

Settings, Sounds and Haptics

Ringtone and alerts - maximum

Haptics - Always play

Ringer/Silent Button - set to Max and On
Settings, Do Not Disturb - Off

This definitely seems to be an issue stemming from the Starkey software.

If you have encountered this issue before or if you have any suggestions, that would be great?

Thanks!