Currently there is no option to remove the size and color measures from displaying on the data tip. This feature should be added as sometimes you want to display only controlled variables rather than variables that make the report.
Additionally, only measures are allowed for color and size options. This should be enhanced so that user defined labels / formats of categorical variables can define the size and color of the bubbles on the map.
Finally I think the size of the bubble should be allowed to be user configurable. The linear / magnitude option which is currently only present in data designed section and not in report designer section does not satisfy the requirements.