Workspaces changed a bunch: https://developers.google.com/web/updates/2017/10/devtools-release-notes#workspaces

There's no more mapping, it's just done all automatically.
I would recommend removing this folder from workspaces and readding it.

At this point you should have some green bubbles on network assets to indicate some of them have been mapped to the source files.

If that's not happening we're either going to need a bunch of screenshots or some version of your project where we can reproduce this.

Thanks

@Reporter: could you please respond to the comment#2 

I have been experiencing the same issue and now I was able to reproduce the bug locally, so someone else please try the same steps. When a folder is added it records all files correctly, but it does not persist on files which have been previously edited through this method. So as long as it is the first editing of the file after adding a folder to workspaces it all works fine, after refreshing the page the file is disconnected and does not record any changes.

1. Add folder to workspaces
2. Edit a file and save it to prove that everything works as intended
3. Refresh the page
4. The file does not have the green mark anymore and local changes are not transferred anymore.

Attached are the steps recorded via the Windows Steps Recorder which showcases the bug.

Deleted: workspaces-bug-steps.zip 1.9 MB

workspaces-bug-steps.zip 1.9 MB Download

@tarik - thanks for providing a repro. Could you attach it in another file format? Couldn't find an easy way to open .mht file on Linux (the Chrome DevTools team uses this as the primary OS for development).

Sure, here is a PDF, the image quality is worse but actions seem visible.

Deleted: workspaces-bug-steps.pdf 2.6 MB

workspaces-bug-steps.pdf 2.6 MB Download

I get this issue with a .less files indicated from a CSS sourcemap.

Most of the files map correctly, however it seems that *source .less files have the same name* are mapped only once.

Assuming you compile this less file and generate a sourcemap.

@import "bower_components/bootstrap/less/tables.less"; //maps to app/less/tables.less
@import "bower_components/bootstrap/less/modals.less"; //maps to app/less/modals.less
//...
@import "app/less/tables.less"; //no mapping
@import "app/less/modals.less"; //no mapping
@import "app/less/foobar.less"; //maps ok

The bootstrap tables.less and modals.less files will have the green mark, but app/less/tables.less and app/less/modals.less will not. 

After upgrading to chrome 63 i can no longer map files using workspaces and have lost the ability to use chrome as an editor.

>>Couldn't find an easy way to open .mht file on Linux (the Chrome DevTools team uses this as the primary OS for development).

I have Win 2012 and cannot get these green marks(this bug appeared first in 'Workspaces 2.0'). My collegue with MAC can get them, but I don't.

1) Maybe You should add tests for Win OS too?
2) How can I help to resolve?

Workspaces 2.0 is imperfect and there's no feasible way to make it work for everybody. Archiving since we currently don't have resources to allocate towards improving Workspaces story.