the red line bar disappeared from yesterday on modern dashboard

If nothing else changed on the dashboard or in your installation, you probably should chat with support to make sure there isn't a larger issue in your environment. That shouldn't just "go away" without something changing. 

Try to monitor 100% CPU.  I think it's because of that.

no all the tables are having same issue 

are they the same device?  I mean are they all APs?  What I would do is to check for patterns.  Are they specific vendor?

bro 

the issue not related to device , all our tables become blank without any changes 

bro, im giving you advise how to better troubleshoot your issue.  if you would find a pattern, then it would be much easier to submit a ticket to support.  I mentioned this on one of your post.  I currently do not have SW environment so I can't duplicate the issue you are having.  I'm just trying to help you out troubleshoot your issue.

Also, the screenshot you showed me are different.  one is CPU and one is memory(and the last oone is interface utilization). The way I see it, it's not even the same widget.

ok bro understood 

it disappeared automatically . this people changing without testing 

I find this an issue when switching to another user without admin permissions.  I create the dashboard as an admin, log in as a customer and they see numbers.