Problem with current QT player and After Effects

Hi,

I have been rendering various animation clips in After Effects 2020 and saving them as Quicktime .mov files which I have been doing successfully on my Mac for the past 3 years but now the message comes up 'The file isn’t compatible with QuickTime Player.' - my Mac upgraded a day or so ago to Catalina 10.15.5 (19F101).

Is there now a problem between After Effects Renders and the current Quicktime Player and if so how do I work around it please?