Resource Override doesn't work on Chrome 84 (workaround: Source > Filesystem)
On Chrome 84 Network and Sources, etc. shows Resource Override URL to URL doesn't have any affect, the extension is no longer working.
After more checking, I find a workaround by adding local path (that is also defined in Resource Override URL to URL) in Chrome DEV Tools > Source> Filesystem. By some reason Chrome DEV Tools > Source > Overrides doesn't workaround it, neither when only using Source> Filesystem.

Could you give more details please? I wasn't able to reproduce. I was using Chrome Version 84.0.4147.105 (Official Build) (64-bit) on Mac OSX 10.13.6 and was able to redirect one website to another.
I reproduced the issue on latest Chrome Windows 10. Used valid regex for URL to URL override.
Valid regex? The url match strings are not run through a regex engine. The "*" syntax is custom. Are you able to post the url strings?
Also just tested on Chrome Version 84.0.4147.105 (Official Build) (64-bit) on windows 10.
I am running into this on chrome 85.0.4183.102. It is a bit more nuanced that the initial report.
I have the following override:
https://static.mycdn.com/*/my-app.min.js --> http://127.0.0.1:8081/my-app.js
It loads the non-minified version from localhost, as expected. This can be seen by the page content and the network tab. The minified version has a 307 (internal redirect) in the network tab.
However, when I go to the sources tab in dev tools I cannot open the non-minified version. The only file available in the sources tab is https://static.mycdn.com/latest/my-app.min.js.
So in summary the plugin is still overriding the page content, but not the dev tools.