What does the upload card in the corner tell me?

How many photos are in, how long is left, and what to do with any that didn't make it.

The title counts the photos: Uploading 12 of 240, then All 240 photos are in. Under it are the size, the time left once it can tell, and how many were here already.
Pause lets the photos on their way finish and starts no new ones. Carry on picks up where it stopped.
▾ folds the card into a small bar with the progress line. Click the bar to open the card again.
If some fail, the title says so, like 238 in, 2 not uploaded. Press Try all again, or Remove the ones that failed to clear them away.
Show the list lists the photos that failed, are on their way or are waiting. A failed one gives its reason and Try again; × takes a waiting or failed photo off the list.
When everything is in, Done puts the card away.

Why isn’t it working?

A photo says Not uploaded: Its line in the list gives the reason. A connection problem goes with Try again; a file that can't be opened needs exporting again, as a JPEG.