CK Version: 2.1,.1
MEP: 0.1.5b+compatibility patch
Additional Mods: HIP installed but not activated.
There is an unmatched parenthesis in the file faction_decisions.txt (in the decisions folder). The decision faction_claimant_ultimatum has one too few parenthesis at the end of it (there ought to be one more after line 1241), so that the parenthesis at the end of the file that ought to end the list of decisions instead ends the decision faction_claimant_ultimatum. This has had the effect of "hiding" the decision faction_antiking_ultimatum; on adding the missing parenthesis, faction_antiking_ultimatum is possible again, and will in fact almost always display as a choice- leads_faction = faction_antiking is the primary requirement in its potential, but, since you have gotten rid of faction_antiking, the game interprets this as "leads_faction = no_faction".
Also, my game keeps crashing ("CKII has stopped working" and exit to desktop) after playing the game for a few minutes. I can't figure out any common theme behind the crashes (i.e., they're not just occurring when opening a character tab, or after receiving an event, or anything like that), so I'm not sure how to turn this into a useful bug report, but I'm curious whether anyone else has had this problem. Neither deleting and reinstalling the mod nor reinstalling CKII has stopped this problem, and I have not had it happen while playing unmodded CKII (not even since 2.1.1, which I understand has caused crashes for some people).
EDIT: But far more important is the following: one of the quotes displayed on loading runs "You shall no pass- Gandalf the Grey". The correct quote is, of course, "You cannot pass."