Screen recording cutting off everything but middle and end of clip

[asdfasdfbeasts]

Hi. I have used Quicktime and screen recording apps reliably on three different macs for years, but I've encountered a new problem. I've recorded my screen for about 25-50 seconds. It only records the first and last few seconds, with the middle being a still frame of where it cuts off. I've tried recording with both Quikctime and another app and the issue occurs in both programs. Any way around this? Thanks!