Sounds like a bug. Your best bet is to open an official ticket on the support site using "Get Support" in the upper right corner.
If this is a known issue they will tell you what version you need to upgrade to in order to clear the bug.
If it is not yet reported you will get it into the queue to be fixed.
I've experianced an issue where it drops the group-mappings when I was running 7.0.6 pretty often. I'm not sure if it was really ever a 'fixed' issue but once we upgraded past that software version we haven't run into the issue sense.
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