In reviewingthe unconstrained path analysis in Timing Analyzer, I see the following:
Timing constraint: Unconstrained OFFSET IN BEFORE analysis for clock "CLK"
Timing constraint: Unconstrained OFFSET OUT AFTER analysis for clock "CLK"
Timing constraint: Unconstrained PERIOD analysis for net "CLK"
However, when you have an unconstrained path crossing clock domains, then this is reported as a standard unconstrained path rather than an unconstrained PERIOD. This is similar to how asynchronous paths are shown as follows:
Timing constraint: Unconstrained path analysis
The timing engine has found paths that would naturally fall into these OFFSET IN/OUT and PERIOD constraints for this given clock signal. Please review these paths and make sure they are not constrainted incorrectly with a TIG constraint or unrelated PERIOD constraint.