The sort order does not stick and defaults to "descending" order when opening the sidebar and making any changes.
This sounds like a symptom of having two different queries overlapping the same cell space, such that the query you think you are editing is not the right one.
To check for this - click on Add-on->Supermetrics->Manage queries to open the SupermetricsQueries tab. In that tab is a list of all queries in the file. Check for the Sheet name that this query is on and check the Range Address column to see if there's two or more overlapping queries. If there is, you can delete the unneeded ones.
If you don't have overlapping queries, then check to make sure you are clicking "Apply changes" when you update the query in the sidebar (else it doesn't save). In the SupermetricsQueries tab you can also force the change there by scrolling over to the Sort column and updating the text there for query: