'Diagram' mode for editing Workflows doesn't work.
STR:
1) Click 'edit' workflow (it does not matter active workflow or not).
2) Switch to DIAGRAM mode.
ACT: Diagram interface does not appear.
EXP: Diagram interface should work.
NOTE:
It's happened after last Jira upgrade,
and NOT connected with the absence flash plugin and incorrect browsers work.
I have the latest Flash Plugin version and tested with all browsers and on the several PCs.