I asked a question yesterday after using the amazing Solar2D Copy to device and launch, I have finally found a bug - it was my own.
Since every once and a while someone comes along with problems with the extension obb files on Android, here are some pointers:
If you have a google package and keystore pass for the app, you can test the obb file on device without having to go through Play store (not sure if you need to upload at least one version to Play store though as I already had mine).
If you have the mentioned package name and keystore pass, you build the app for Google Play using Corona/Solar2D simulator - you get the app + obb files only using Google Play.
On your device create a folder and name it exactly like your app package name (com.testsite.appname) in internal storage in a folder Android/obb. You will find other similar folders in there. It didn’t work on SD card in my testing.
You put the obb file (main.123.com.testsite.appname.obb) in the folder you have just created.
Now you can install and run the app - note if you delete the app, both folder and obb file will be deleted, so you’ll have to repeat the process.
No matter what number is used in the obb file name - main.123 or previous main.122, it still works, so you can specify in Play store that the update will use previous obb file.
I hope this helps…
Thank you Solar2D