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This problem initially occurred when I was first trying to upload my previous article. I was concerned that I had lost the entire article. Luckily, after I opened a new window, I found that the entire article had uploaded without any problem. Meanwhile, in the original window I had left open, the PUBLISH icon (which also appears as the UPDATE icon whenever modifying an existing article) was still buffering indefinitely.

Yes, that is what happened to me, too.
I figured I'd check to see if it posted in another tab, and it had, so it is functioning, just not in the expected way.