It's a known issue for almost a year and a half now:
Issue:
Orion NTA cannot collect CBQoS and mapping information when SNMPv3 is used, authentication is set, SHA and privacy protection are AES256, and private mode is selected. If you use these settings, you can find errors about authentication in the Core.Jobs2 log file, such as: 31016: Authorization Error - User does not have rights to requested MIBs.
Solution:
If you want to use CBQoS NTA polling, do not use Orion NTA with SNMPv3 when authentication is set, SHA and privacy protection are AES256, and private mode is selected. Turn off authentication, reset SHA and privacy protection, and deselect private mode.