After update new version of dashboard 2.0, the chart loses the value of the second parameter if it is the same as the value of the first and does not draw a line.
Welcome to the forum @teluse7
Please post a small flow so that we can try to reproduce the problem and thus understand it better.
Include an inject node withf a sample of the data and the chart node.
What dashboard version do you have?
When exporting and pasting your flow, in order to make code readable and usable it is necessary to surround your code with three backticks (also known as a left quote or backquote ```)
```
code goes here
```
See this post for more details - How to share code or flow json
