Migrating SSRS 2008 to 2016 - ReportSync cannot see Data Sources
Thanks to McNets for the heads up on the map DataSources option. To solve the problem I had to:


Load up both servers as per the image in the question
Select Tools > Map DataSources
I was getting a runtime error at this point this was stopped by creating a datasource on the target server and clicking the "Load" buttons again in ReportSync
The resulting window shows all the source server datasources with a dropdown list next to each allowing selection of the target server data sources
Recreated all source server data sources on target server (including all the details - connection strings, authentication etc...
Using the map datasources option, assign each source server data source to the relevant target server data source
Click set
Click sync at the bottom of the main window


The test report I created now opens