How to use file replacements in Angular 10

Question

I am working on a project, and as far as I can tell; when running "ng run build --prod" the file replacements are not working.

This is important as I want to remove the NgRx devtools when putting the application into production. Otherwise it runs slow

What is strange, is that if I run another custom-build configuration("debug-without-devtools") it actually works.

I can prove it has worked by trying to access the dev tools while using the application.

This is what I'm working with:

Angular: 10.0.2
... animations, common, compiler, compiler-cli, core, forms
... localize, platform-browser, platform-browser-dynamic, router
Ivy Workspace: Yes

Package                            Version
------------------------------------------------------------
@angular-devkit/architect          0.1000.1
@angular-devkit/build-angular      0.1000.1
@angular-devkit/build-optimizer    0.1000.1
@angular-devkit/build-webpack      0.1000.1
@angular-devkit/core               10.0.1
@angular-devkit/schematics         10.0.1
@angular/cdk                       10.0.1
@angular/cli                       10.0.1
@angular/material                  10.0.1
@angular/material-moment-adapter   10.0.1
@ngtools/webpack                   10.0.1
@schematics/angular                10.0.1
@schematics/update                 0.1000.1
rxjs                               6.5.5
typescript                         3.9.6
webpack                            4.43.0

Any help is appreciated

Thanks

Andrew