copy/paste of image into comment in a transition screen is broken

Issue Summary

Copy/paste of image into comment in a transition screen is broken
While commenting an issue in the issue view it is possible to copy/paste by using CTRL+Z an image in both Text and Visual Mode, to get it automatically added to the comment. In Text Mode the image is converted in thumbnail while in Visual Mode the image is uploaded with his real size.
While copy/pasting the image in a comment in a transition screen, the functionality is broken. In Text Mode pressing CTRL+Z does nothing while in Visual Mode the image seems to get inserted but after triggering/confirming the transition, the image is not available and appear broken.

Steps to Reproduce

1. Transition an issue that has a screen set for that transition
2. In the transition screen comment field copy paste an image by pressing CTRL+Z in Text Mode
3. In Text Mode observe that pressing CTRL+Z does nothing
4. In Visual Mode observe that pressing CTRL+Z actually attach the image, but then after transitioning/confirming the screen, the image is not actually attached and show as broken:
   

Expected Results

Image should be inserted by pressing CTRL+Z

Actual Results

Image is not attached

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available