We recently had an issue where our change notice workflows, (completely OOTB) began to fail. This was not reproducible in Stage or Development so as you can imagine, this was a bit of an issue. Either way, the solution was rather simple. Clear the expression cache. I had never heard of this before and I figured I would share it with everyone. So, without further ado, how to clear the Expression cache out.
**Remember to do this on all nodes if running a cluster**
Navigate to ---> Windchill\codebase\wt\workflow\expr