Bulk discovery fails for devices configured with SNMPv3, but when quick discovery is run, it is successful for the single device.
Probably the same SNMPv3 Engine ID is configured for all network devices under a single scheduled discovery. This results in discovery not performing well and failing to discover devices correctly.
Check that the network devices do not have the same engine ID configured on the SNMPv3 settings. The SNMP Engine ID must be unique for the administrative domain so that no two devices in a network have the same Engine ID.