Follow these instructions to get an out of stock notification app working with Best Custom Product Options.
- Go to Settings
- Turn On Allow Pre-orders, or Allow selecting sold out variants.
- Click Save, to save settings
Allow selecting sold out variants will still show the sold out styling but you can still select sold out products allowing an out of stock app to work
Allow Pre-orders will show the options normally with no sold out styling which allows out of stock apps to work.
After this your out of stock notification app should work properly.
This app is compatible with ours