So today I decided to take pics of the "magic appearing bubble".
Repaired break as normal - drilling was used in this case, but minimal, and in a fashion suggested by Screenman. "Dabbed" resin out prior to applying pit filler.
You can see better in the mirror as the camera focused there instead - there is no bubble.

Closer...

Lamp applied - 4 mins - sunny day.

Lift the lamp off after 30 seconds - BAM! It's there...

Closer...

The otherwise good, but now spoiled finished repair...

Closer...

Prior to this repair, I didn't use a tab, that had a bubble too. (It was the reason I took pictures of this second repair).
So I'm stumped

Any advice would be appreciated - except DryStar's - as you seem to "separate" yourself from poor technicians like myself (your words).
Cheers,
Pommy