I started using the ribbon a few weeks ago in Rhino WIP (currently on 5E169w), and have experienced more frequent crashes. For example, with the ribbon enabled, the BooleanDifference command will hang indefinitely, while with the same file, same geometry and the ribbon disabled, the same command will perform as expected.
I love the ribbon, but it’s too unstable for me to use right now.
2016 MacBookPro, 10.11.6, 16GB RAM.
Unfortunately, I’m unable to reproduce this crash. Please let us know if you can reliably reproduce this on your end with repeatable steps.