Considering what you, and I'm sure others, cite, I have some newish thoughts on the subject.
I think that the FDA may have initially halted the trial (in August 2015) at the prompting of the DMC (data monitoring committee), whom I believe had ulterior motives, given that we later determined that the head of the DMC was also on an SAB for a Swedish company working on a competing solid tumor dendritic cell vaccine, and that his brother was on the board. Please note, after this was brought out on this board (by me), both of these positions were suddenly removed from the website of the competing company. But, it's very possible, then, that when the FDA looked more closely at the unblinded data of the trial (which I believe they would have access to, while the company remained COMPLETELY AND UTTERLY blinded), they first would have seen control patients that were eventing later than the treatment arm because the treatment arm was showing false progression - pseudo progression / psPD - due to DCVax-l that couldn't be measured correctly due to the antiquated progression determination criteria). But at the same time, they would have also (likely) seen that progression in the treatment patients was also disappearing with time. The FDA may have also seen from the data that some of the control arm patients that were crossing over were also demonstrating psPD after crossing over, that later went away. Finally, as Linda Liau had indicated in October 2015 in a videotaped presentation, all of these patients were living longer (impressively longer, IMO, otherwise, why say it then?). All of these data points would have indicated to the FDA that the trial had issues in both arms, but the safety profile was such that all patients could continue treatment. And there is the interesting fact that the treatment arm was fully enrolled, and the control arm was what, 16 patients short?
Now... as you and others have pointed out, if what I've laid out in the previous paragraph was indeed the case, the FDA would not have been able to share any of these reasons with Northwest as it would have compromised the trial and the integrity of the data moving forward.
It also could have resulted with Northwest privately feeling that the FDA may have also not been operating with honest intent, given that it would seem that the DMC certainly wasn't. Again, if this were the case, I don't think the FDA could share with Northwest their exact reasons for halting the trial. And when Northwest indicated in a public PR (I think that was in Feb 2017 or 18? - I can't remember exactly when) that they would no longer be enrolling the trial and had decided to move forward with the data they had, the FDA lifted the halt within a week or so later. Now those who aren't invested but post here 24/7 will have you believe that the reason for the lift was because NWBio indicated that they would no longer pick up enrollment in the trial. I'd argue, then, why bother lifting the halt ... just leave it in place. But lifting it does telegraph something... IMO... that the reason for the halt was not a bad one, and instead, as you, DocLogic and others often contend, rather an indication of DCVax-L efficacy, meaning... the vaccine works.
Anyhow, thought I'd post my thoughts on this, inspired by your post. :)
AI
