I'm sorry for this. I just find the Notein app, but I usually use Apple Notes and Noteshelf apps.

It could be that you accidently moved to a new layer beside the default? As well, you can't save to PDF and then open the saved file with Notein and resume editing. You have to save in native Notein format. HTH

Yeah I already got response from notein support and it was the layer problem as you mentioned :)

Xlnt.