If " Evt_Reboot" sql table has no records, means that non of managed computers are requiring reboot now after patch updates installations (you can double check whether default patch report "Restart Status" shows any records about pending reboot)
Looks like 8.0 HF6 also has ' Inv_Software_Update_Distribution_Status' sql table so please check it on your environment instead of 'Evt_Reboot' sql table.
Corrected/Updated information also in separate discussion (https://www.symantec.com/connect/forums/evtreboot-table-not-populating) to mention that 'Evt_Reboot' sql table contains data only from 7.x managed client computers and other 8.0, 8.1,8.5 will send reboot state events only in Inv_Software_Update_Distribution_Status' sql table
Thanks,
IP.