I had immediate regen problems with my 2018 (fully up to date) B3350 from the day that I brought it home.I would not expect a problem with a low hour B3350, even on my Nov, 2007, I had no issues for hundreds of hours.
BTW, if the tractor dies and the instrument panel is dead, check for a blown 5 amp fuse. If it blows again, it's a short to ground inside the neutral sense switch on the forward/reverse treadle. Common problem. I bought a new switch, but haven't installed it. Just took a 1/2 PVC female threaded pipe cap and screwed it on the switch mounting threads to hold the switch engaged, insulated switch and nylon tied it to the nearest wire/tubing to get it out of the way. I've decided I'm smart enough to keep my foot of the go lever while I'm starting the tractor.
My saga has been recorded here in times past and I will not reproduce it now.
A retired electrical/computer engineer who designed engine control computers for a major American Automobile manufacturer (both hardware and firmware) in one of my former lives, I understand why Kubota threw in the towell on the mechanically injected, reformer based DPF system.
SDT