[Chart Series Label]

On the Data Configuration tab of the HTML5 Chart Edit Dialog, you need to enter a value in the Tooltip Expression textbox. I used an empty string to get the null to disappear.

Alternatively, under Advanced Configuration, modify your Measure Label Exrpression to an empty string.

 

[Chart Series Label]

I am having the same exact issue. No answers....?

 

[pass variable from subreport to main no work]

Try changing the Evaluation Time of the Textfield used on the master form to "Band" for the variable.