Strange issues in GSC after moving site to HTTPS

[Miks2019]

I recently moved my site to HTTPS. When I was reviewing index coverage in GSC, I noticed about 10 pages that were excluded with the explanation "Duplicate, submitted URL not selected as canonical". When I started digging, I noticed that Google selected HTTP version of the URL (i.e. http://example.com/something/) as opposed to HTTPS version (i.e. https://example.com/something/) that was specified as canonical. I am wondering why is this and whether I can do something about this? There is absolutely nothing special about these pages.The sitemap submitted to Google has all pages in HTTPS. The entire site is redirected to the HTTPS with 301 redirect and all other 200+ pages have been properly indexed as HTTPS according to specified canonical version.

[aristotle]

Did you conduct some search tests to see which version google shows in its search results?

Also, GSC can be slow to update to the latest status

[not2easy]

You are seeing these results in GSC under the https: version of your site? Once a site is properly sending request for your old pages via 301 rewrite, you should be able to watch the old version become de-indexed in GSC as the "new" domain becomes indexed.