I have tried the image for Buster from the Download page for OrangePi PC Plus, and also built new images from current Git repo.

In all cases the device bootloops when it tries to start the kernel.

 

The image from the OrangePi website works ok.

 

This looks like a similar issue as experienced recently with CubieTruck and BananaPi A20 boards (https://armbian.atlassian.net/browse/AR-749) which was fixed with a workaround (https://github.com/armbian/build/pull/2963)

 

Is it possibly the same / similar underlying problem?

 

Since H3 is 32bit Allwinner as well it could be affected too, yes.

As mentioned a fix is already applied so either wait for next release, try nightly images or build one on your own from master.

@Werner  Thanks.

 

I have updated my master and built new images for the CubieTruck and for OPi PC+.

The new CT image worked but not the OPi PC+ image.

 

Is it possible that the fix has not been applied to OPi PC+  /  H3 as yet, or is the fix inherently common to all Allwinner 32bit devices? 

All 32bit Allwinner SoC share the same firmware packages IIRC. Maybe some further adjustments are necessary to get everything on order again.

@Werner  Thanks.