How to see/use Target Audience column in SharePoint Designer Workflow (SharePoint 2013 Online, Designer Workflow)

Question

Hello,
I'm attempting to use use the Target Audiences field in a SPD 2013 workflow, in this case just attempting to log the value to history for testing purposes.  This is failing saying the column does not exist.
I enabled Audience Targeting on the list then create a simple workflow to log the value to history when the item changes.
I change an item and the workflow starts, but when it gets to any action looking at "Current Item:Target Audiences" it stops and says:
HTTP BadRequest to <site url>/_api/web/lists(guid'XXXXXXXX')/Items(4)?%24select=ID%2CTarget_x0020_Audiences 
The field or property 'Target_x0020_Audiences' does not exist. 
But it does.  It is listed in the list setting and enabled for the content type.
I ran the listed API through an API program and sure enough, Target Audience is not listed in the results object.
I'm 99% sure I've enabled this and that the field is present and the workflow is valid.  I ran the same situation on two lists to ensure it wasn't a hiccup, same results.
Is this a know issue?  I couldn't find anything obvious online saying you cannot see this field via workflow, most of what i found said this would work.
Thanks an advance for any input.

Answer 1

Thanks so much Lisa, for the clarification.
I understand what you have explained, and have seen several similar explanations that have lead to my confusion.  Can you elaborate a bit, maybe for the sake of future information seekers?
I understand that audiences can be defined using the rules operations in Central Admin, but it seems another standard function is to just directly assign existing SharePoint groups.  I think this is what you mean above, but this is also the point of
my misunderstanding.
In this particular setup I have only used existing SharePoint groups with no audiences defined in Central Admin.  List Item A has a target audience of SharePoint group X, just that simple of a setup.
Assuming the above is valid, I would then like to see or alter the groups via SPD workflow.
Based on the following posts, I was under the impression this may be possible (but obviously not fully clear and thus I posted this):
https://social.msdn.microsoft.com/Forums/sharepoint/en-US/5eb984ba-55a3-4da7-a904-c34b2fece84c/how-do-i-set-the-target-audience-using-sharepoint-designer-workflow
http://www.sharepoint-tips.com/2011/01/setting-target-audiences-with-code.html
(sorry about lack of links, my account must still require verification)
So in SPD, I set a simple action such as "Log Current Item:Target Audience to history" (note the I am able to select target audience in SPD like any other field with no errors).  At this point I am assuming everything is valid as SPD is treating
the field like any other string field.  When executed the error in the above post comes up.
So to confirm your explanation, this is not supported?  Even though the field is available for selection by design, it is not capable of use and known to produce errors in all cases of its use?  The first post above is 100% wrong and you cannot
use SPD to set/view the target audience field?  The second post is also wrong as it seems to present the fields as available for alteration using string concatenation?
 If in fact the field is present by design, but also impossible to use by design, is this potentially a bug as the field is not supposed to be available if it will always produce the error when used with no error in SPD during compile?
Thank you again for the reply and I hope we might be able to provide a rock solid answer to this for future seekers.