Email Invalid - Wont let me create an account

Ive been using this app for a few years now. Long ago I thought I had created an account to start backing up the data. When I got a new phone recently I couldnt sign in to that account so I had to create a new one and export the existing data to the new app/phone. Now that I KNOW I created the account, I cant sign in or back up my data. Keeps telling me the email is invalid. When I try to create a new account with a different email, same thing: email invalid.

Please fix this and help me back up my data!!

Alissa Kirby about Period Tracker Deluxe, v9.4.1