Missing fuel rod reported at incorrect Y location

[HumanBean06]

Hello! Playing Project Architect 2 v3.6 with biggerreactors-1.20.1-0.6.0-beta.10.4, and i built a 64x64x64 reactor, but when I finally assemble whole reactor, it does not form a multiblock. I have placed entire interior (fuel rods and moderator) with Building Gadget and 'Construction Wand,' exterior with wand. (building gadget made it soooo much easier i wasted so much time with the wand lmao)
Right clicking gives me this error:

Those coordinates are about 150 blocks below the reactor, but within the bounds of the base of it.
After this happened the first five times, I went and replaced every control rod by hand in case if that was it, but the coords changed a couple times, but error did not go away. Then i go down to coordiantes below reactor to place fuel rods and casing in varying arrangement to try and satisfy condition. no luck
Thank you!