VO Recording breaking up / Jittery Timeline Bar
I'm not sure of the best way to explain this...I was trying to add a voice over track (in French) to a previously completed video (which has a different VO track, in English). I have everything muted except the new VO track. The blue timeline bar (probably the wrong name) jitters and is jerky when recording, and the VO is breaking up badly on playback.
I have exported the file and the VO is quite smooth, except for a slight crackle at the end of 3 minutes.
Latest version of Premiere Pro (2019). Windows 10, 64 bit, 16GB Ram. I've tried the project settings at Mercury Playback Engine only and GPU acceleration. Neither seems to be better than the other.
Can someone advise on what setting I need to change if any, please?
Thanks for any suggestions.