proxy stutters in source monitor plays fine when directly imported

Created proxies in encoder from hevc to prores proxy with a maximum height or width of 960 whichever being greater with a lot of different aspect ratios (1920x1440, 3840x2160, 2160x3840, 1440x1920, etc). the proxies will stutter and stop and not scrub in the source monitor as an attached proxy but when imported directly there is no playback problem. The original hevc file plays fine and scrubs well...I transcoded as I like to work in intraframe for all the obvious reasons but this is a pain in the ass. So the question is why...