Ok - So I figured this out the hard way... Decided to create a copy of my workbook and started with my problematic dashboard.
From the dashboard I removed all but one of my sheets (9 total) and posted to server. Success!
Ok, so I then started adding sheet by sheet and posting as I added sheets one at a time until I found the one that breaks my publish. Wouldn't you know it would be the last sheet I add the breaks the publish.
So now I know where and in what sheet I'm having a problem. From there I start to remove pills from the sheet until I can successfully publish. Found the suspect!
Turns out I was using a reference line that was set to "Total" when it should have been "Sum" It worked!
Ugh...something so simple, yet the error had me going in many different directions to find the solution. Nothing like a little trial and error to fix a dashboard.
I went back into my prod copy of my workbook and made the change to my reference line, publishes to server beautifully now.
I will remember this one for sure...