Do you know that you can add to Diagnostics operation as many aliquots at a time as it can be viewed in Aliquot Catalog?
When you are adding aliquots for testing in Diagnostics Operation using Magnifier button, the Aliquot Catalog is opened. The maximum number of aliquots, which you can select at a time, is limited to the number of aliquots displayed on one page of Aliquot Catalog.
To increase the number of records per page on Aliquot Catalog, go to System -> Preferences and modify value in “Number of records per page in catalogs” as needed.