I edited a music video that went out to a post house for the colour correct. I received back clips with one second handles and relinked it all. There are a number of nested files and speed ramps (time remapping) in the original project. It all playbacks as it should in the Premiere timeline, but the exported file has many frozen or stuttered frames.
I am working with ProRes 4444 3200 x 1800 from an Alexa Mini. I am exporting to the web a H264 file, but I've tried changing the codec flavour, using software and hardware only for the export engine or straight out of Premiere. I'm running a 2017 iMac and High Sierra. The files are on an external G-Tech drive linked through USB 3.