Weirdly enough, this still happens to me with regular CivUp and GEM, without modifying InfoTooltipInclude.lua. The tooltips start off fine, but at some point, the building tooltips start omitting much information. After playing a few games, checking the tooltips each turn, I think I've found it: the tooltips go nuts on the turn I meet a new civilization! Weird, right?
Attaching a lua log for one game, where I quit the game just after the tooltips broke.