Upgrade angular 10 to 11 - template interpolation no longer working

Question

So i've been trying this a few times but was too busy to follow up on it.

Now I want to migrate on to version 13, i'm doing 1 version at the time. But the same issue still exist (even if i skip on to 13).

When upgrading to Angular 11, template interpolation just stops working resulting in all the templates filled with things like {{message}} (there are no errors in the console and everything else works perfectly fine!)

I've used the Angular Upgrade feature which said all code was fine and we only needed new packages. We are running hybrid with AngularJs though, which also means we use the custom webpack builder for the AngularJs template compiler, translations and legacy jQuery expose loading.

I can provide lots and lots of code snippets and files (and will update my question if someone wants a specific file) but was hoping someone knew anything about this without having to paste all the config files. Maybe just someone saying, ah we had this too, it's this 1 line that you need.