If you have multiple widgets that have the same value set for library, only the assets from the first widget on the page with the same library value are loaded.

To help visualize this issue, I have 3 widgets (BSelect, DateRangePicker, and Datatable with rowgroups) on the page and this is the resulting css hrefs to be added. Note the primary value in the first and last entries are the same. This results in KRDataTables.css and datatables.min.css not being loaded from the last entry.

This appears to be a problem in KoolReport.js where checkLinksAndCallback() is not called in these instances. To test this theory, I added this.checkLinksAndCallback(); to the end of the registerLink method and things worked as expected.