I have found that the budget barchart will not display accounts with children. It turns out that the report has code that skips accounts with children. To get the desired behavior I changed the following starting at line 208:
      ;; Else create chart for each account
      (else
        (for-each (lambda (acct)
          (if (null? (gnc-account-get-descendants acct))
            (gnc:html-document-add-object! document
              (gnc:chart-create-budget-actual budget acct running-sum))))
          accounts))

to 
      ;; Else create chart for each account
      (else
        (for-each (lambda (acct)
		    (gnc:html-document-add-object!
		     document
		     (gnc:chart-create-budget-actual budget acct running-sum))
	    )
          accounts))

and got the behavior that I expected.

Perhaps this is fixed in a later release as when I look at the source on github at https://github.com/Gnucash/gnucash/blob/master/src/report/standard-reports/budget-barchart.scm I see that the report functions have been reworked.