perplex, vex, stick, get, puzzle, mystify, baffle, beat, pose, bewilder, flummox, stupefy, nonplus, gravel, amaze, dumbfound (verb)

be a mystery or bewildering to

"This beats me!"; "Got me--I don't know the answer!"; "a vexing problem"; "This question really stuck me"

complicate, perplex (verb)

make more complicated

"There was a new development that complicated the matter"

perplex (Verb)

To cause to feel baffled; to puzzle.