Issue Summary

When a chart is connected to multiple variable controls, and then one of those variable controls is deleted, this causes the rest of the variable controls connected to the chart to vanish when editing the underlying query in Visual SQL mode. The connected filters vanish only when editing the query, and then reappear again after running the query. 

Steps to Reproduce

1. Connect a chart to 2 or more variable controls
2. Delete one of the connected variable controls
3. Open the chart editor in Visual SQL mode and edit the query 
4. Once editing the query, the connected filters disappear temporarily
5. After running the query again, the connected filters then reappear

Expected Results

We would expect the dropdown filters that were not deleted to still appear in the query under the "Filters" section when editing the query in Visual SQL mode. 

Actual Results

The filters disappear when editing the query, and then reappear after the query has been run. Please see the following screen recording for a live example of this bug: 

Vanishing filters bug.mov

Workaround

Currently, there is no known workaround for this behavior. A workaround will be added here when available