Previewing image upload in a reply hides your reply when closing the preview
- Reply to a post
- Attach an image to your reply
- When the image is uploaded click the preview button on the image
- Close the preview with ESC or by clicking the corner X
The post you were writing isn't lost, but you have to click the post button in the top nav bar to access it again. May also affect other upload types, haven't tested.
Win 10, FF Dev edition, up-to-date.