Yes the UEF Experimental EFOF Transportator (Tech 3 Experimental Transportation Spaceship) can't be build
But it's not a mod bug. This bug is from the game and only occur on Experimental transporters.
Game patch is ready and will be patched into the next game version:
https://github.com/FAForever/fa/pull/3248
Ok, i will upload the updated mod this evening.
I want to play some AI testgames with it to be sure my AI can handle all mod updates.
(there are some more fixes, i never uploaded)