This is because we don't sync Access Control groups for the following reasons:
1) They deemed to have no function outside of Domino
2) They don't have an SMTP address and so don't get picked up by the connector
To resolve this issue, if the groups are required in AD/Exchange then carry out the following:
1) Create a new group with a similar name, making sure the Group type is either: Multi-Purpose or Mail Only
2) Run the Directory Connector and the newly named groups will sync across.
1) Change the Group Type for these groups to either Multi-Purpose or Mail Only
2) Run the Directory Connector
3) Revert the modified groups back to being Access Control List only.