Bluetooth stylus pairing no longer available


I am not sure what happened, but Notes Plus seem to no longer support bluetooth stylus pairing nor pen function on older models of iPads anymore? I have been using Notes Plus for many years now with note taking.
When I try to re-pair my adondit bluetooth pen, the “digital pens” drop down list is now empty and you cannot select the bluetooth pens anymore.
Is this function taken away from newer versions of Notes Plus?
I need the ability to pair bluetooth pens to the APP so that I can take notes with palm rejection as I am left handed.
Now, without the pairing, taking notes on this APP became unstable.
Can anyone help? What can I do? Or do I need to somehow return to older versions of Notes Plus where they still supported digital pens??
Thank you.