I am receiving the following warning in MAP:
Why are all members of the time group optimized out of the design?
There are two possible causes for this issue.
1) A case-sensitive mismatch in defined UCF constraints.
In this case, you should also observe similar constraint system warnings in the Translate report.
2) The associated elements of this time group are trimmed because they are unused.
You can refer to "Section 5 - Removed Logic" in the MAP report for detailed information on trimming.
In this case, you would need to ensure that the design is complete so that there are valid timing paths for analysis.