Thanks for the details. They were enough to track it down, and it's fixed in 1.8.2, which is out now.
The cause: Nullius starts you already wearing its chassis armor. MK11 saw the armor slot was taken and put the suit in your inventory unequipped, with an empty grid. That's why there was no reactor. Nullius also recalculates your running speed whenever armor or equipment changes, which kept overwriting the MK11 speed bonus.
What 1.8.2 changes:
On a new game, MK11 swaps the Nullius chassis into your inventory, with all its equipment intact, and equips MK11 with the reactor, laser, and roboport already installed.
The MK11 speed bonus now stays in effect after Nullius recalculates speed. Taking MK11 off leaves Nullius's own speed bonuses alone.
MK11 now loads after Nullius, so its changes take priority.
On an existing save:
If the empty MK11 is still in your inventory, just put it on. It gets the starter loadout the first time it's worn.
If it's already on but has no reactor, type /mk11 in chat to re-grant the kit.
Nullius hides all non-Nullius recipes, so the MK11 parts can't be crafted there. /mk11 is how you get the kit back after losing it.
Speed presets are on the MK11 panel (the MK11 shortcut button), or Ctrl+scroll by default.
I tested it with Nullius 2.0.11 on a new game (starting kit, speed, swapping armor, and respawning). Switching between Nullius android bodies wasn't tested, so let me know if anything misbehaves there.
