The ER.org app doesn't seem to have this issue, so I suspect it was just a Tapatalk problem. Glad it's resolved now.
I've gone through the reset process two times now via the emails that ER.org sends describing the procedure for resetting passwords.
The problem persists.
Can log in and access on my PC, but not on my phone. The same password is being used on both devices. I am using the same email address for ER.org that I have always used. I have not changed any settings on the Tapatalk app on my phone.
Irrelevant.