I have some workflows that show the graphical prieview correctly and some that do not. After searching here it appears the common fix is to delete anything disabled in the workflow. The problem is there is nothing disabled that I can find.
If this matters, I took a known working workflow, made some updates, saved it as a new workflow and published. The original will show the prieview, the updated revision will not.
Any suggestions on where to look?
Thanks in advance.
did you have set any rules or expressions?
I occured the same issue because of a some errors in a expression of a rule.
Try to disable all rules and try to open a preview to check if the problem is related to that.