Since I figured out what was wrong with the sitemap for my blog site, I’ve been getting more posts indexed. But Google is still fiddling with the other sitemap, the one for the photo gallery, and can’t seem to decide what to do with it.
Click on “Sitemaps” in Google Search Console and you get a display showing the maps you’ve submitted, and how Google is (or isn’t ) using them. Here’s what I have now:

The first entry is the sitemap index for my photo gallery. At this point it seems to have been successfully read and parsed. Click that entry and you see the story on the contained sitemaps:

The second entry is the actual map for all the image pages. Looks good, 649 image URLs found.
But over the last few weeks, that information has changed many times. The status flips between “Success” and “Couldn’t fetch”, and the number of URLs is sometimes 600+, sometimes 0. Apparently “Couldn’t fetch” is an erroneous message GSC puts up while it’s processing the file, but it may persist for days. This is what I see today:

On a better day, in the top level sitemap display there may be a little gray icon to the right of the map, like this:

In my case, that icon is sometimes there, sometimes not, it’s come and gone several times. If it’s there, clicking on it gives detail about the indexing status of everything found in that sitemap:

This display shows the important stuff: whether Google has really indexed anything. Right now all my photo pages (660, circled in green) are shown as “Discovered – currently not indexed”. This means Google has parsed the URLs, knows about those pages, but hasn’t really looked at them yet to decide whether to index them. They could just shorten this to “in limbo“.
A few pages (3, circled in red) are “Crawled – currently not indexed”. This means Google looked at them and decided they weren’t worth indexing. This could be shortened to “no thanks“.
The weird part is the gray bar graph up above, showing the number of “excluded” pages over time. “Excluded” includes both of the categories below, it doesn’t mean they’ve been rejected yet, just not indexed. This number has jumped up and down over the last few months. One day Google knows about all my URLs, the next day it seems to start parsing the map all over again from scratch.
How will this end up? Eventually Google should start working through those 600-plus photo pages and decide whether or not to index them. When that happens I’ll start seeing some changes in the “Coverage” numbers.
UPDATE: stuck in limbo
fascinating account. Sitemaps provide little impact btw. They DO tell Google you’ve got new content, but dont provide much more than simply being informed about the new content ahead of them finding the content on their own.
I came here just for info about smugmug custom domains
Yeah who knows. At this point it seems like Google makes no real use of the ‘gallery’ sitemap, it just puts all those URLs on a “maybe someday” list and forgets about them. I’ll be writing another post soon with my updated Google score.