Go to one of your questions or answers and paste in a URL whose destination is inside of TSE (this is important).
In some cases the program goes and looks up the link and translates it into readable English (and impressively so). In other cases, the program ignores it and presents the raw URL (disappointingly so). Could it be a bug?
What is the rule governing this? Or alternatively is there a tip I can use to make it work every time?
The authoritative source is What limitations does converting question links to links with titles have?
For links within the same site, the only limitations I know are stated there:
Short links to answers, like https://meta.stackexchange.com/a/108475, are not converted. Long links are converted: What limitations does converting question links to links with titles have?
https links are not converted in preview, but are converted after posting: What limitations does converting question links to links with titles have?
