Do you only have one tag in the tags tv?
That search searches for resources where the TV is exactly "Sundarburns".
Use
&tvFilter=`tags==%Sundarbans%`
to search for anything that contains your tag.
That will cause tags like "Development" matching "Web Development" too tho.
If you’d rather not have that, you’re probably looking at creating your own snippet to get matching resources, explode the tags tv by the delimiter, and see if it still matches using in_array(..,..) and only return it then.