I've never tried that specific scenario with tabcmd and setting it up takes a while but I as a method of troubleshooting, have you tried creating a calc with a parameter as a filter for the secondary sources? like
[parameter] = [field name] replace your dimension filter with the calc and set to true. (make sure your parameter is set to "All" and that the current value is a value that exists in the data)
Then test to see if that responds to the URL parameter being passed. If that works it could be a possible work around.
I'm not using any Tableau parameters in this scenario. I did try creating a calculated field that simply references the original field being used as a filter. I switched my dimension filter over to the calculated fields. It works in Tableau Desktop, but still no-go with tabcmd export. I've also upgraded to 8.1.
Hey Brian -
I haven't tried this in ages, but the following used to work - I'd give it a try...
Lets say you have two data sources: DS1 and DS2. Each data source has a field name named "Terrible Pop Singers".
You want DS1 to be filted by Myley Cyrus and DS2 to be filtered by Justin Bieber (if you are offended by my choice of terrible pop singers, then we need to talk). Here's what the command might look like:
http://tableauserver/views/MyWorkbook/MyDashboard?[DS1].[Terrible Pop Singers]="Cyrus"&[DS2].[Terrible Pop Singers]="Bieber"
Like I said, I haven't actually tried this technique since back in the Tableau 7 days, but it worked once upon a time...