Lightroom Classic Publish Services fails to publish to Flickr; Flickr API returns error message

[helen_glazer]

Two weeks ago I was using the Publish Services in Lightroom Classic 11.5 with no problem. Now I have 5 new photos to add and I keep getting an error saying "Flickr API returned an error message (function upload, message nil)" or "An error was encountered while trying to access Flickr server."

I tried removing the Authorization in Lightroom Publish, and then putting it back. 

Basic steps:

Add photos from Collection to Publish Services: Flickr: Photostream.

5 photos are in New Photos to Publish.

Click "Publish."

Wait a long time while the progress bar says it's uploading, and then the bar turns red and returns an error message.

It is also acting wonky in saying there are 3 Published Photos and then it said there were 507 "Modified Photos to Re-Publish" and then the next time I attempted it said there were 759  of those — when I have not modified any of them recently. And both the Published and Unpublished have "!" on them, and say the previous location is an external hard drive I only use for traveling, which makes no sense at all. I'm tempted to delete them all from the "Modified Photos to Re-Publish" in case that's what's causing the error, except I'm concerned that will also delete them all from Flickr, which I do not want. But if that won't take them off Flickr, let me know.

I am on Mac OS 12.4 Monterey.

[helen_glazer]

By the way, I right-clicked on Publish Services: Flickr, created a new album with the 5 new photos, and this time they uploaded. So apparently the modified photos in the Photostream are the problem. If anyone has insight into what to do about those, let me know. It would be nice if changes I made in Lightroom were in fact automatically synchronized with Flickr, and if I have to create new albums for every upload, I lose that ability.