Third-party Battery not recognized

Dell machines and 3rd party packs have always been tricky since the DX30 Sony recall :-(. They use a custom TI battery gauge IC with the E series (and now the 4 number/[screen size] Laptop/Plus Laptop) and the battery manufacturer has to say DELL to avoid tripping it. The main issue is most 3rd party packs do not properly spoof the vendor IDs, which is how Dell knows.

The issue is Dell no longer makes batteries for these machines, so you need to find a decrypted battery - you are not finding this easily on sites like Amazon because of how hyper paranoid sites like Amazon are. I don't have a ready source, but you want to look for one which claims 100% compatibility or on other sites, look for clues it's fully decrypted.