Links embedded in the buildRow method of the ConfigEntityListBuilder class get converted into html text tags. Other methods of the class leave embedded links alone. I suspect its some kind of twig function or a filter being applied somewhere but I couldn't find any relevant documentation about this. Anyone know?

Re: [SOLVED]

The output of the buildRow method of the upstream parent EntityListBuilder class is being passed through the String::checkPlain() method. There is even a test in EntityListBuilderTest which states in its comments: 'Tests that buildRow() returns a string which has been run through String::checkPlain()'.

To confirm this on my development server I allowed text to flow straight through checkPlain() and the links out of the buildRow method stayed as links. I then wrote a workaround so checkPlain could resume its purpose and am using the workaround to continue what I was doing before I was sidetracked.