Flickr plugin does not "replace" when uploading after elimination of Flickr Pro accounts

Question

When uploading an image to flickr it has been possible for Pro accounts to re-upload a photo and replace an existing upload. This "replace" functionality keeps intact any comments, ratings, "favorites" etc that the photo has accumulated on the Flickr website since the original image was uploaded. The Lightroom Flickr plugin (authored by Adobe) has always correctly limited this "replace" functionality to Pro accounts (flickr did not allow the API call for non-pro accounts).
With the recent flickr policy change eliminating Pro accounts, flickr has enabled the replacement functionality for all users. However, the Lightroom flickr plugin still performs a check for a Pro account and does not attempt to replace a previously uploaded image if a user has a non-pro account (which is now all accounts that were not grandfathered in as Pro). The plugin currently uses the older behavior of first deleting the image and then uploading a new image, thus losing all comments, history, views, bookmarks etc that the old image has accumulated.
There is another non-adobe flickr plugin, and the author of that plugin stated on his web site that simply using the old Pro "replace" API call now works for normal flickr accounts.
I recognize that this flickr policy change happened recently, but I'd like to be sure that Adobe is aware of this change so that the next point release of Lightroom will include a change to the built-in flicker plugin to remove the check for Pro accounts and allow all users to replace photos. I used this feature a lot when I was a pro subscriber, and I think all flickr users of Lightroom would appreciate this change. It is still possible for all users to replace an image on Flickr by exporting to a jpg from Lightroom and then uploading the replacement through the web site, but enabling the plugin would obviously be better for customers.

Answer 1

I worked with Gokul from Adobe support, and we eventually stumbled into the solution.
The system clock was wrong! 
Based on something Friedl says on the blog for his Flickr plugin, the Flickr authentication APIs will fail if the system clock is wrong.  His plugin helpfully points out that the clock is wrong when you install it.  It also reports the error that he gets from the Flickr APIs: HTTP 401 (not authorized).  Unfortunately, Lightroom's builtin Flickr publishing plugin doesn't report any error, and it just fails silently.
In my case, Windows appeared to be displaying the correct time, but the time zone was incorrect, and my system time was actually 3 hours ahead.  I reset the clock and timezone and restarted Lightroom.  Now, the builtin Flickr publish plugin is working again.