Unfortunately it was always problematic. Besides bugs and problems with the actual implementation there were some more logical problems too. One example is if a user has 'fixed' an outdated link by removing it from the page. Scrutiny would simply re-test the url it has and continue to report it as a bad link. The fix for this is convoluted. Given that the user may have altered anything on the site since the scan, it's slightly flawed in principle to simply re-check urls that Scrutiny is holding.
There's often a more specific reason for wanting the feature rather than a broad-brush 'recheck all bad links'. For example, the server may have given a few 50x's at a particular point and the user just wants to re-check those. Or the user has fixed a specific link, or links on a specific page.
After working with a user on this, we found a solution that answered the above requirements, while being more sensible in principle.
From Scrutiny 6.2.1 (and soon in Integrity 6 too) the Links views (by link, by page and by status) allow multiple selection. Context menus then give access to 'Mark as fixed' and 'Re-check selected'.
It is possible to select all urls, or all bad ones. All urls on a particular page or all urls with a specific status. It is still possible to re-check a link which may no longer exist on a page, but if the user selects the url and chooses the re-check option then it's illogical but it's a deliberate action on his part.
6.2.1 is currently in beta, the link below will download it and will give 30 days use.