Summary

Pasting an image into comments produces different results across instances and OS, sometimes a pop-up will appear which deletes any comment that is the progress of being typed, other times no pop-up appears and the markup

!image_name.png|thumbnail!

is inserted directly into the comments and the image uploaded.

Also when the pop-up does appear it removes any comments that are in the process of being written, usually where the image is intended to be inserted.

Steps to Reproduce

1. Create an issue
2. Write a comment and copy & paste an image into the comment while writing.

Expected Results

Consistent behaviour that attaches the image and doesn't remove the comment. If pop-up appears the image should be attached and the markup placed in the comment to include the thumbnail.

Actual Results

Behaviour I have observer (all tested using Chrome 70):

On my instance the following:
OSX + Mouse = Pop-up
OSX + Keyboard = Pop-up
Win10 + Mouse = No pop-up
Win10 + Keyboard = No pop-up

*Customers instance: *
OSX + Mouse = Pop-up
OSX + Keyboard = Pop-up
Win10 + Mouse = Pop-up
Win10 + Keyboard = Pop-up

Whenever the pop-up does appear it removes the comment that was in the process of being written and was the intended destination for the image attachment.

Notes

Instance details in internal comment to protect privacy.
I have also attache HAR files of both observed results.

Workaround

Paste the image directly into the issue without selecting inside a comment field as this will create a pop-up where the image can be uploaded and a comment added at the same time.