Hi Paul,
The crashing might be due to anomalies with Mac OS X.
Try the following:
- Sign out from Creative Cloud, restart Premiere Pro, then sign in
- Update any GPU drivers
- Trash preferences
- Ensure Adobe preference files are set to read/write
- Delete media cache
- Remove plug-ins
- If you have AMD GPUs, make sure CUDA is not installed
- Repair permissions
- In Sequence Settings > Video Previews, change the codec to one that matches your footage
- Disconnect any third party hardware
- If you have a CUDA GPU, ensure that the Mercury Playback Engine is set to CUDA, not OpenCL
- Disable App Nap
- Reboot
Report back if anything here worked for you.
Thanks,
Kevin