Scanner Service picks up info for only RPM packges on Linux machines.
Please refer to Report Center Guide which does have detail list of information captured on various Unix platforms.
For Report Center 8.1.01 guide, information is available on pg.281
What is not getting captured? Patch information or hardware Inventory or software inventory or all?
Can you connect to your database and check the table called inv.application_view? and refer to this link:
What is the result of the query?
In some of the linux endpoint the installed software has been captured, but in some it is not capturing.Also the scanner version used is 8.1.01.005..