I've seen that quite a bit...never understood why. Though it seems to go away the second time I check the file in.
Since you are using the configuration name, you may have to activate that configuration and rebuild it to get EPDM to resolve.
If you figure out what causes this, please post back. I'd love to know.
In early versions & service packs of EPDM 2008, I found the reason for the mentioned issue.
While the SW file custom properties are being reviewed during "Checked-Out" state, I too found the EPDM data card would only show custom property expression instead of evaluated value.
The moment when the SW file gets checked-in, I found the issue is resolved. I mean the expression is evaluated during Check-In time and then EPDM showed the evaluated value.
So, I think this issue seems similar to me as mentioned above. So I would suggest to conduct such EPDM actions (Check-In/Check-Out, Get latest version, rebuilding the file in SW application etc...) to see the difference in results between multiple EPDM operations, thereby you might be able to identify the real reason for it.
If the issue persist during every EPDM operation, then it could be treated as bug and you might need to work with your VAR/SW directly.
Hope this information helps....