Help please with DPF regen

[V12noise]

M57 35D

Had the Particle Filter warning on the Dash, so looked at the fault memory with ISTA+ and saw the relevant errors were 480A and 481A.

Did the pressure tests at idle and 2000rpm and found the pressures to be just under and just over the thresholds, respectively. Last regen was around 3500km ago and a whole lot longer before that - probably due to faulty thermostat.

From various threads and youtube, worked out I had to delete the Fault memory and then request a regen. This appeared successful and the ISTA status page said Regen Enabled and while I drove RegenStatus went between InActive and Active for a while, and then stayed Inactive.

The final transition to inactive was at around 10 mins after clearing the fault memory and I guess the 480A error had come back. When I looked at the fault memory again, sure enough the 480A was there.

The question then is how to get through this? Do I need to make sure I don't get inactive before the regen is complete? I guess I need to delete the fault memory and request the regen just before getting onto the motorway...?