Crawled - currently not indexed. Some list items are now almost a year old

The usual advice is to ignore Google Search Console's "Crawled - currently not indexed" and accept pages that end up here will be indexed eventually unless there is something wrong with them.

Today I visited this category for the first time in ages - there are always more pressing problems to deal with. I found there are pages that are crawled and still not indexed almost a year after they were crawled.

The most recent are five months old.

18 of my pages have this status.

Each of the pages appears in the sitemap and is accessible through other links on my site - although possibly not enough other links.

If I test the live URL they look fine.

Google's documentation says there is no point submitting these pages.

What is going on here? Is there another way to wake up these pages and get them indexed?