I using the "Network" tab of the developer tools to view the submitted form data in my application. I've tested using Chrome, FireFox quantum, and Edge. I can only view them in the Chrome browser.
Can anyone tell me why?
Note that the application works well with all browsers.
Here is the screenshot 
In Edge (Microsoft Edge 44.18362.449.0)
Press F12
Under Network. Select your POSTed page.
Select the Body tab and click Request Body.
(There are two links under the Body tab: Response body and Request body.)
One thing I've noticed (and this might be your problem) is that you should have the debug screen up first (press F12). Do this before you POST.
Page will look something like this:
In Edge, Body > Request Body have the data that you are looking for. Please refer Edge Help
And for Firefox, please refer MDN webdocs
I was trying to login to a website using a Python script for which I needed to find the form-data header but couldn't find that for long until I came across this YouTube vid: https://www.youtube.com/watch?v=SvUqk683mSA where they say that you need to make sure to check Preserve log on the Network tab of the developer console because apparently the Network tab clears requests activity on every page refresh and therefore the user-login POST request would never be visible.
And once you do get the login request you were looking for, in order to get the username and password or any other form data, head to the Payload tab and you'll find your "form-data" under Request Payload. Hope this helps!
