I have noticed that some of my rules give false positives, i.e., they flag segments that are in fact correct. I have been able to narrow down the reason and it seems to be that these rules have anchors (beginning and end of segment, ^ and $ respectively) both in the source and target. These are RegEx rules in PowerSearch. If I remove the anchors in the target, the rule works as expected. Is there a limitation on the use of anchors that I should be aware of?