Miscba I am no expert by any means but I would say that the VCI has been profoundly impacted by the selective mutism and that it's possible even the other indexes have been impacted to some extent too given that she has a significant anxiety issue.
It's not the most common thing for WMI to be the highest from what I understand, but it's certainly an asset to have a strong WMI.
The WMI tests mostly involve parroting back letters and number, possibly re-ordering them first. So the ability to hear, hold and manipulate then spit back out increasing volumes of random data. This is something that your DD might not have much anxiety about getting "Correct", if she is good at it she may not have underperformed because she did not feel that there was any wrong answer. Where as the VCI is all about talking and the PRI tests might still trigger some anxiety because she has to make the right choice.
I would imagine that to have any hope of getting an accurate measure using a psychometric test it would probably need to be administered by someone your DD can talk to (relatively) well. Does she see a psychologist for the selective mutism? Could they be the one to (re)test her?
