Error when using live connection to Power BI dataset "An error occurred while loading the model"

Hi v-qiuyu-msft I'm having a very similar problem as reported by RobJo here. 

• a MASTER .pbix hosted in a sharepoint location, and then connected to from the service (from 2 different workspaces - this was pre the new shared and certified datasets option).
• Thin reports created by conncecting to the MASTER dataset in the Power BI service. This has worked fine for some months.  
• Same error message as reported by RobJo since Friday and therefore unable to open any thin reports.  
• The problem is an older workspace. The other new workspace, which connects to the same MASTER .pbix in sharepoint location works OK. However I do have a very similar MASTER v2. pbix which is working fine in the older workspace. 
• Though I cannot open the thin Reports .pbix in Power BI Desktop because of the error, all the reports in the service and working and refreshing still.  

I have created a new blank report, then tried to connect to 'Power BI datasets', and while I can definitely see the dataset there, I get the same error. Can I share the Trace with you? 

Thanks,

Patrick