[NTG-context] Strange Behaviour of \mathop

Dear list, I stumpled upon a very strange effect that \mathop has on the vertical positioning of characters. \mathop applied to a single character results in the character's baseline being lower than the baseline of all other characters. This does neither depend on the font (checked with Lucida OT, Pagella and LatinModern) nor on the specific character. A minimal example for LatinModern and Pagella is attached. With kind regards, Tobias