After a recent update from TYPO3 6.1 to 6.2 on a site that makes use of the new sys_category function, I noticed a strange behaviour:

Even though categories were shown in the front end and, if viewed with the list tool in the backend, also showed as defined, they were not selected on their according pages.

In page-edit view, the pages would not have their categories attached - none of the categories were checked. But the correct categories were shown on these pages in the front end.

Back in the list view of the categories, a click on info on a ...