After closing the problem project and opening it again, the behaviour is back to normal. But at one point I had the problem project and the nonproblem project open at the same time and it worked on the one but not the other.
Steps for issue: (n" is move distance constraint, commands are on command line)
LMB object > Move > Enter > LMB drag > <<n">> Enter = “unknown command ’ n” ’
Same for offset
LMB line > offset > Enter > (D > or) <<n">> = “unknown command ’ n” ’
It seems that it was a semi-crash of some kind where distance inputs are concerned.