Andrew, I have the exact same problem. I can create new notes. When I try to open the old notebooks I see an image at the top left of the screen that looks like black pages. These seem to indicate the number of pages that were written in that note.... touching them does not open the page or do anything at all. I'm going to delete the app and start again..... done... had to sign in again to Evernote.... after it synced up, which took 10 minutes all the notes were there and accessible. Good Luck!
I have used Penultimate fore years and it has never allowed for pasting of text. I have taken screen shots and imported them in to P. to do that you hold the pencil against the screen and pause a moment and the prompt will come up to allow you to paste. Good luck.