Sounds like a bug.
When you see system epoch date 12/31/1969 or 1/1/1970, it means the file never gets update
after it has been checked in. Somehow repository API never go to find version comment if the
the file has epoch date stamp.
If you check out a file, modify it and check in again, you'll see correct date and version comment
from the output.
Please open a case with SAP.