Many thanks again.

So I can confirm that satnav upon resuming back from sleep and with BT turned off in my phone beforehand misbehaved again, i.e. there were no camera warnings present on my trip back home.

Which doesn't surprise me really as this idea of checking the entitlements remotely by the device was a long shot really, and I doubt it's taking place.

I can also confirm that device still did see the relevant PoI files - as evidenced via 'About...' menu section - I specifically re-checked it.

I will look Universal Firmware Patcher up at convenient time - one is never too old to learn something new! - but at this stage will concentrate on investigating other PoI files I might have owned and used in the past (including the ones I used to have from Garmin).

Nonetheless my thesis still is that it's the fluffy Garmin's firmware (device software) that is the root cause here. I used to own 3590 before nüvicam, and some of the errors I witnessed there are present in this device as well.