Last night I had an issue similar to your wife’s. I had repeatedly been turning my HA external mics off and on to avoid feedback as I donned and removed ear muffs to protect the HA’s from water as I went outside to check sprinkler function at the various stations that come on over time in our yard.
One HA failed to come on and was disconnected from the Smart 3D app. Earlier in this thread, I mentioned a thread I had started about occasionally losing connectivity to my Omnias that I attributed to the iOS 16.3.1 upgrade: iOS 16.3.1 and Connectivity Issues. In this instance, last night, rebooting the phone did not reconnect my Omnia. I had to reboot the HA. The issues I described in starting that thread have happened to me about once a day, and I only noticed them since getting iOS 16.3.1 in mid-February.
I noticed in the iOS MFi accessibility settings (Settings, Accessibility, Hearing Devices, MFi Hearing Devices at the top of the screen), there is the option to control the HAs independently or not. Changing this option to controlling both together in the iOS accessibility settings doesn’t seem to affect whether or not both HA’s are controlled together or separately in the Smart 3D app. But I’m wondering if things work out better if both HA’s are set to be controlled together in the basic iOS settings. Maybe my “iOS 16.3.1” issues are related to what’s going on with your wife’s HA’s, and it’s not a battery issue but some HA connected/not connected, HA mics on/off issue related to electronic circuits and their software/firmware control, not the batteries. My “creative” thought is that if my iPhone is talking to both HA’s separately, it’s easier for one of the MFi connections to go astray. So I’ve set both HA’s to be controlled together as MFi devices and will see if that affects my “iOS 16.3.1 connectivity issues.”
If your wife swipes down from the top of her screen on the right, she should see the iOS widgets. If one taps on the ear symbol (I forget if anything is necessary to make it appear), she’ll get direct access to the MFi HA controls. Triple-clicking on the right side button also brings up those controls. In the future, I’m going to see what the MFi settings have to say about connectivity vs. the Smart 3D app. Down at the bottom of the iOS MFi HA settings screen (you might have to scroll), there is a MIC on/off radio button choice.
I notice in fooling around just now that the MFi settings don’t always reflect the Smart 3D app settings, particularly with toggling the MFi mic control on or off. So perhaps part of the problem is the basic MFi controls built into iOS are not always on the same page as the ReSound Smart 3D app connections.