I have found a bug that fits the description of this problem (CSCdt19877)
and it is supposed to be fixed in 12.1(8a)E3 code for the MSFC2.
Workaround
The problem happens because of the following offending line in the running
config of the Non-Designated Router (NDR)
boot config bootflash:
The aim is to remove this offending line from the config of the NDR and
save the config and reboot. It can be done either by doing a config t on
Designated Router (DR) and then doing a no on the above config. (It would
get synced to the other side), then do a write mem on the DR to save the
config and then reboot the NDR. The other way to do that is disable the
config sync on the DR, which would allow you to go into config mode on the
NDR. Then on the NDR do a no of the above command and then follow it with
a write mem and reload of the NDR.
Let me know if this helps.