I was unable to get an app to run offline. I spent easily 2 full days working on why. Finally saw the problem. In my extraFiles folder there was a .php file. I normally don’t put this type of file there but because I have to delete my server deploy folder before doing a full deploy I thought I’d make life easier by not having to always reinstall this .php fle. Big mistake. Removing this made it work. Is this something AS needs to look into or is this something that is a no-no for pwa apps?
An easy workaround is to put the php file(s) in another directory on your server (at the same level as the app) and reference that folder when ajaxing to the php file.
No errors appear in the Console, but if you go to Application/Cache Storage/your_app, it will be empty. A good deploy (Full deploy required, not F7) will populate this area with the cached files needed to run offline.