Naze32 Acro Motor Sync Issue

I’m kind of a noob with quads, so please go easy on me if this issue has been asked and answered. I looked but I couldn’t find a solution to my specific problem, which is this:

I have calibrated the ESCs in Baseflight. When I spin the motors up using the Basegflight Motor Test function, they are all in sync and work perfectly. However, when I arm the board and use the Tx throttle, one motor (No. 2) takes longer to spin up and runs quite a bit slower than the others.

I’m stumped. Any ideas?