Well, it states in the FAQ that the LTSC may not work on hardware that came out after the latest LTSC release. Then again, I have no idea when that was or whether that’s more of a general statement that usually doesn’t hold true. Regardless, something to think about.
Personally, I’d install vanilla Windows 10 and then debloat it using one of the many reputable tools out there.
[Edit] This might also shed some additional light on the matter, if indeed the problem is with storage (and if you were using your old LTSC ISO instead of an up-to-date one).