We just upgraded OMS from 13.2 to 13.4, and found an Oracle BI Server target ‘obis1’ is listed as a part of the GCDomain, and it is shown with status DOWN in EM Console.

CAUSE
It is a bug. The target ‘obis1’, shown with Down status, is a an unwanted target that got introduced as part of the upgrade to Version 13.4.
SOLUTION
Ignore the target or just delete it using EMCLI.
$ emcli login -username=sysman
$ emcli sync
$ emcli modify_target -name="/GCDomain_GCDomain/GCDomain/obis1" -type="oracle_bi_server" -properties="DisabledTargetTypes:oracle_bi_server"
Target "/GCDomain_GCDomain/GCDomain/obis1:oracle_bi_server" modified successfully
OR just delete this target.
$ emcli delete_target -name="/GCDomain_GCDomain/GCDomain/obis1" -type="oracle_bi_server"
Target "/GCDomain_GCDomain/GCDomain/obis1:oracle_bi_server" deleted successfully