Ran into the same basic problem, and still can't find any explicit support for "Verbose" mode in Simple XML as of Splunk 6.5. However, that being said, a very simple but effective work around is to simply add a
| fields * to your search.
<base search> | fields * | ...
You could try adjusting the settings for the saved search that drives this visualization. In savedsearches.conf, there is a display.page.search.mode setting that allows you to set the mode.
See also this previous Answers discussion for more info and possible limitations on the setting:
Hope this helps!
I figured a workaround, by adding
fieldname=* fieldname2=* to the search, it added them to the output in fast mode. I would like to still find a way to force it to verbose mode in a dashboard if that is possible.