Invalid name character in 'Extended Properties'. The ' ' character cannot be included in a name.

[Jaffa]

I have a 2016 workbook connected to an Azure DB data source via Power Query and Power Pivot. I get this error on all my data tables when attempting to refresh from within the workbook on Power BI.

Error: Invalid name character in 'Extended Properties'. The ' ' character, hexadecimal value 0x20, cannot be included in a name. 

Ideas welcome. What is most frustrating is that I uploaded the workbook before doing most of the work on measures and content, just with the data, and it refreshed fine.

Edit: There are no extended properties in the connection strings that I can see, they all just take the format

Provider=Microsoft.Mashup.OleDb.1;Data Source=$Workbook$;Location="Customer Details"