audio jumps to next frame rate - premiere pro
I think you should try aligning only the audio when you do this.  The video tracks have to be aligned to the nearest frame, because video is either showing frame 1 or frame 2 (assuming your sequence frame rate is the same as your footage frame rate).

Audio is sampled at a much higher rate than video.  e.g. your video could be 25 frames per second, but your audio could often be 48kHz, so sampled 48,000 times per seconds.

Your ears can detect very small variations in delay between audio files (of a few milliseconds), and your ear/brain/eye combo can detect very small discrepancies between audio and video lip sync (22ms according to this).