Take a look at your MAF. If it's made in Germany, swap for the made in China one. I went thru what your going thru. Took them 4 months to resolve. However, I think my resolution was temporary as the issue is likely in programming. I'm also of the belief it is the lack of cetane in fuels. Most stations sell basic stuff with 40-42 cetane. Needs to be closer to 48. The slower ignition is likely leading to incomplete burns which creates both more soot and reduced EGTs which make passive regen nearly impossible.
With that said I got a new maf. Solved nothing even tho it was the german one. Tried CCV, Air filter, DPF and much more from May to August last year before returning to me saying it was fixed. Since then, all but 1 regen was a 24 hour regen until April this year. I've had a couple 5 hour, 200 mile regens. After those two I dumped Archoil 6400D in the tank - went 450 miles and about 9 hours with no regens. Lately I've run Archoil 6500 at 3 oz per 10 gallons. I've had nothing register on the gauge since I had the two 5 hour 200 mile regens cycles with a return to the 24 hour timed regens.
With the above info I really do think it's a combination of programming and poor USA diesel cetane ratings cause the shooting issues. The 6400d and 6500 seemingly increase cetane (performance is much better, especially when you need to scoot in a hurry) while reducing the EGTs necessary for passive regen.
Hope this helps