This is the query I am trying to run against EF7
_context.Event.Where(e => e.Invitations.Any(i => i.User.Id == currentUserId));
Fairly simple query indeed and I can't see any non-boolean phrase passed as a condition.
Event here is in a one-to-many relationship with
I am posting an answer accepted by the OP: looks like there is a known bug in the sql generator, a bug the team is aware of: