Virtualbox OSX: Problem booting to "macos installer" volume created by 10.15.2 update

[ziffster]

Existing APFS Catalina 10.15.1 installation on VirtualBox 6.1.0 with Clover 2.5K 5098 worked fine. I could boot to both the main Catalina volume and to the recovery volume with either the EFI Shell or Clover.

So, I intsalled the 10.15.2 update, which created a new volume (two actually, if you count the extra "preboot" volume also created). However, although I can see the new volumes in Clover, and also in the EFI Shell (boot to file), I can't boot to them. When I try to boot to the "macos installer" volume from the EFI shell, either via the preboot volume or directly, I immediately go to a black screen and hang - no text shown. If I try with Clover, I get a line of pluses, then hang.

However, I can still boot to the original Catalina 10.15.1 and recovery mode volumes as before, from both Clover and the EFI shell. So all of that still works, but I'm stuck on 10.15.1.

Why is it hanging? Is there some step I'm missing in the EFI Shell? Since I can boot to Catalina itself, I don't see why the updater volume won't boot. Is there some way to run the installer from recovery mode? (I know you can "reinstall OSX" from recovery mode, but I want to run the specific updater volume which appears as "/System/Volumes/Data/macos Install Data/".)