Disk imaging with Acronis (or similar)

I realise this is similar to this thread 

https://www.lattepanda.com/forum/topic/312397

but that's sort-of gone down a Linux route, which is not where I'm at!

I've need to image some LP devices (as what needs to be installed takes too long for roll-out) and have run into the following:

I have a bootable acronis 2017 USB stick, and USB SSD.
I can boot into acronis and create an image on the SSD no problem
I then go to my target (2nd) device, an reverse the process - boot to acronis, clone back onto the LP

Initial trials were successful, but now I'm trying to roll this out cloned devices are now randomly failing to boot post-clone.

It appears as if the LP BIOS is trying to boot into the wrong device - it now has two entries for Windows Boot Manager, + the USB stick (even though it's not plugged in). So If I go into the BIOS and boot-override into one of Windows Boot Manager entries, it works, the other fails, but setting either entry as the default boot device is ineffective.

Any suggestions? And is there an easy way to reset the BIOS - load optimised defaults does not clear the record of boot devices.

Thanks in advance

Zip!