In reply to sharvil111:
This was a bug in the OVM that was not corrected until UVM 1.1b.
Note that there are other UVM bugs with comparing associative arrays. If you were to do
a.syndrome[2] = 0; // sET A VALUE IN ONE OBJECT ONLY that matches the default
b.syndrome[1] = 5; // sET B VALUE IN ONE OBJECT ONLY
you still will not get any error. It only iterates over the elements in A.
In any case, we strongly discourage the use of the ova/uvm field macros for their poor performance.