The BCAAA log displays numerous 1221 events:

BCAAA: [4284:4412] CheckTokenMembership() failed; status=87:0x57:The parameter is incorrect.

AuthGroup 'DOMAIN\Group' does not exist; status=1789:0x6fd:The trust relationship between this workstation and the primary domain failed.

Event ID 1221 occurs when an AD group that does not exist (or no longer exists) is referenced in policy on the ProxySG.
This can be caused, for example, when you delete a group from AD, but do not change rules that use this group on the SG. The proxySG does not check, upon policy installation, whether a group exists or not. Instead if compiles a list of all groups that are referenced in policy and asks the AD about them. These are the so-called groups of interest (GOI).

It can cause excessive log entries in BCAAA because the event is logged every time the appliance evaluates a rule where the group is defined.

Usually, the event contains details about the group to investigate. You must locate the policy rules where the group is defined and disable or remove it to verify that the events stop occurring.

If the event log entry does not show the offending group name, you will need to enable BCAAA debug logging as per this KB article: Enable BCAAA debug logging

In the resulting debug logs, you will then see the name of the group that is referenced in SG policy but that no longer exists (or no longer is accessible) in AD. For example:

2015/11/12 14:17:07.691 [5376] Failed to look up group GroupName='foobar', error 0x800400b8