Hi DarrenOD,
According to your description, the bubble map can display correctly in visual studio, but after deploying the report to report server, it will display incorrectly, right?
As Ricardo suggested, please check the Data Source and Data Sets of the report in report manager if you are deploying to report server. Make sure the report is referencing to the same data source and dataset as in the visual studio.
Since you mention you are running the report in IE, would you please check if the report can work fine in other IE versions? You can change the IE Browser to different versions and always run the report in IE Compatibility View mode to find a best IE
version to run the report.
1. Launch the IE, and press F12.
2. Click Emulation icon on the left of the bottom and in the User agent string dropdown list select a supported version.

Besides, when we create a map with Layer Wizard, the data field is predefined with sum() or count() functions based on spatial and analytical data. We can only select those existing fields from the drop-down list. Its not supported to specify any field
with other function in wizard. However, after finishing the wizard, we can specify the field with expected function as data field in Map Layer Size Rules Properties. Please refer to screenshots below:


If you have any question, please feel free to ask.
Best regards,
Qiu