Rohloff now only gives 13 gears

[JohnR]

I would add that if the bolt hole is M6 then the head of a socket head bolt fits the groove in the OEM axleplate as shown on the attached photo.

[Dunroving]

It is my understanding that Rohloff is trying to make hubs that can fit in a through axle frame.  The shifting mechanism is within the axle of the hub, so it is not really through axle.  But, I could be wrong, maybe you have a new design for the hub?

I think a steep uphill and your hub would have started rotating in the frame.  But it would stop rotating when either the EX Box jammed into the chainstay or the gear cables prevented it from rotating further, I am not sure which way it would have rotated.  The torque is strong enough to have cracked frames that were not built for the stresses of disc brakes.

If you have any removable thread locker (Locktite is a common brand), you may consider removing the nut, adding a drop to the threads, and re-installing.  Removable is usually blue.  You do not want it to fall off.

I suggest thread locker on all rack bolts, shoe cleat bolts, fender bolts, brake bolts, and I might think of some other things later.  (Not water bottle cage bolts, seatpost bolt, stem bolts, on those I use grease.)  But a lot of bike shops do not even have a bottle of thread locker anywhere in the shop, so they are unlikely to tell you what I did.

I think you are right and that although I have a through-bolt, the "through axle" is actually part of the Paragon modular dropout and not the bicycle frame itself.

[Dunroving]

I would add that if the bolt hole is M6 then the head of a socket head bolt fits the groove in the OEM axleplate as shown on the attached photo.

Pretty sure mine's an M5 (not close to the bike at the moment).