I tried the same as described here by George and the apps I tried would not load from the browser when offline but would run when a Home icon is made in either PC or Android computers. I tested both AS versions 6.last and version 7.last with the same results.
Concerned that this was a possible issue I added /index.html to the end of the address in the browser and the apps then worked when in offline mode as they should. Apparently a Desktop or Home Screen icon launcher uses the correct URL. This could be of importance when launching from a browser and the app needs to run another app from the same server. Appending /index.html to the location could prevent issues.
Using the /index.html extension om my Galaxy S9 gives an icon with a chrome logo in the corner. Chrome asks you to “add shortcut to homescreen”. Without the extension chrome asks to “Install app” and the resulting icon has no chome logo.
With 'Make PWA?" set to true my apps don’t run offline but do if set to false. Is this expected? I was under the impression PWAs ran offline ok.
Apologies if this is fixed in newer versions of AS. I’m running 8.3.0.2 to enable editing of my projects that have jQuery controls.