Scenario:
(Search keywords: SSRS multi-value-parameter hard-coded values default value FetchXML CRM)
I've created a multi value parameter and manually entered lots of labels/values.
I've gone to the default tab and picked on one of the values.
Copied the changed report up to the CRM using the XRMToolbox ReportSync tool.
Run the report - the default(s) aren't as wished (or in my case didn't seem to have worked at all) so I changed them, re-pushed, and they still don't work.
Issue: A little exploratory testing seemed to indicate that the CRM isn't paying any attention to changes in the default value(s) when I push the new version of the report up. (Note that I'm not doing a publish all because there are other users on the system - not sure if that would have made a difference.)
Solution: Or one, and easy in my case because I'm trying to get the parameter defaults sorted before I've actually used it anywhere: Change the parameter name and re-push. (Then change it back again if you want.)
[There might be other solutions like changing some of the values - not sure.]