The Image Factory

The Image Factory (not the Image Gallery) is like a decoding control panel. It is found in:
  View - Image Factory (CONTROL+I)
Image Factory shows you the status of the current job, what is waiting, and what failed. You can view your attachments, delete them from disk or from the queue, or move decode jobs up or down in the queue.
The Image Factory has some basic file management tools; you can delete files from disk, rename attachments, and so on.

PAUSE and RESUME   Take note of the button in the center of the page. It is a toggle marked PAUSE or RESUME. This allows you to pause decoding or resume.
If you see hour glasses in Gravity's thread pane but nothing is happening, decoding is paused and you need to "Resume" when the connection is re-established.
Related option:
Tools - Global Options - Decoding - "Resume Decoding after connection is established"
When this option is enabled, decoding will begin automatically upon reconnect. If not checked, you will have to RESUME decoding manually in Image Factory.