Good afternoon, Dojo's. We received assistance in another thread (https://goo.gl/i5cVjC - thank you @RGranada!) but needed to expand upon the original beast mode to determine a completed percentage for only certain individuals as opposed to company-wide and @Valiant suggested it's best to open a new thread for this request for visibility.
Here goes! The original solution worked but we didn't realize at the time of the request that it would divide the specified agents by a company-wide total, and not the total of just the offers that Jane Doe or John Doe had worked themselves (since one of the fields used was a date, we made one change - Settled from SUM to COUNT).
We've attempted to update the second part of the original beast mode, trying dozens of variations based on the initial solution; while most attempts validate, they always return an error message ("You have a divide by zero error in your Card’s Beast Mode") when added as a series. We have the ability to use either Settled1 (date field) or Settled2 (a 1 or 0).
Below is the company-wide beast mode that works for all departments, including ours (1), the original Beast Mode w/update mentioned above (2), and a couple of the attempts made to isolate just our call center group (3 & 4); hoping someone can help identify the error(s).
Please let us know if more infomration is required, and as always, thanks in advance for your time & assistance! 
1)
Company-wide Conversion% (settled and completed would be either 1's or 0's
CASE
WHEN SUM(`Settled`) = 0 THEN 0 ELSE
(SUM(`Completed`) / SUM(`Settled`))
END
2)
Call Center ONLY (specific agents piece works, but dividing by company-wide settled):
COUNT(CASE WHEN `Owner` = 'Jane Doe' OR `Owner` = 'John Doe' THEN `Owner` END)
/
NULLIF(COUNT(`Settled`),0)
3)
COUNT(CASE WHEN `Owner` = 'Jane Doe' OR `OfferOwner` = 'John Doe' THEN `Owner` END)
/
NULLIF(COUNT(`Settled` = '1') AND `Owner` = 'Jane Doe' OR `Owner` = 'John Doe'),0
4)
CASE WHEN COUNT(`Settled`) = 0 THEN 0 ELSE
COUNT(CASE WHEN `Owner` = 'Jane Doe' OR `Owner` = 'John Doe' THEN `Owner` END)
/
COUNT(CASE WHEN `Owner` = 'Jane Doe' OR `Owner` = 'John Doe' THEN `Settled` END)