#1 Sourcing parts
This may be a reason although I've seen P90Ds start production after mine go through completion. Again, it's a rare car now, so this could be likely nonetheless.
#2 Quality issues, i.e. misalignment
41 days in production, you could make the MX five times over. If they are sending this and paint to another department that's backlogged, I could see it as a possibility.
#3 Paint correction. As above
#4 Additions upgrade
Everything seems standard. I did get all upgrades but sound. I heard the tow package can add a level of complication in build?
#5 Software
I did order full AP, but nothing is out yet, so that couldn't be it. What if the system OS is acting up, like a blue screen of death and they can't figure it out. Maybe they keep replacing parts of the computer to get to the bottom of it. This could be a reason, a stretch, but plausible.