File recording dropped frames

I was setting up a project to record a window of a application. When I went to record this window I would get dropped frames. My drive is super fast so I know that wasn’t an issue. When I changed the file record to Program Output no dropped frames. Is this a bug or am I missing something?
Ultimately I’d like to be able to record a application window and some mimoLive calls as ISOs.
I get the same result across different hardware too.