@codr1 can you install the advanced reboot package? This gives you a webUI option to reboot into the different partitions. I believe the davidc502 build linked above comes with this. If you're stuck in the old CC build I'm honestly not sure, like said above it should flash in a round-robin where it always flashes the other partition (i.e. the one you're not running).
Here's the thread for advanced reboot: Web UI to reboot to another partition (for Linksys/ZyXEL dual-partition routers) and to power off/power down