VoWIFI works when using the app but breaks after WiFi disconnects

[eranlot]

Hi
When installing and running the app for the first time (OR the first time after network reset), VoLTE works great (now no longer needed as it is official after the March update) HOWEVER VoWIFI (before and after the March update) suffers from the same problem:

1. VoWIFI will ONLY work after manually adding ims APN.
2. Once disconnected from WiFi (either due to disabling WiFi from settings or leaving home / work) ims becomes unregistered / unavailable (and therefore no VoLTE, too).
3. Turning VoWIFI from settings will restore ims / VoLTE, but not VoWIFI.
4. Network reset WILL restore VoLTE however causes to lose both WIFI passwords and BT connections (and deletes ims APN)/
5. Manually adding ims APN will restore VoWIFI, again.

Since VoLTE is officially supported now we use Pixel IMS only for VoWIFI (Partner, Israel).

Downgrading from 1.2.3 to 1.2.2 doesn't solve the problem.

Any suggestions?