Workflow design - AX 2012 - An unexpected error has occurred while opening the workflow.

Working on workflows, had to create a bunch of customized items for an existing workflow:
 - new provider;
 - new computed values for the evaluation conditions;
 - etc.
I kept getting either error messages like this one: "An unexpected error has occurred while opening the workflow. See the event log on the AOS and contact your system administrator to resolve the issue." or the newly created options would not appear in the workflow designer. 

I tried a couple of times AOS restarts and a few other ways to get it to work, and then I realized something that should have been done always when working with components outside the AX's MorphX: perform a CIL Generation after changing your objects. Make sure you have a full CIL done at first, and then work our way up with incremental CIL.