Can't resend an invitation for an endorsement or ask for updating an existing endorsement

Hi,

whenever I try to resend an invitation to write an endorsement or ask someone to update an endorsement, I get the following line on top of the screen: Please correct the marked field(s) below. But there are NO marked fields anywhere on the screen, and I end up being stuck in an infinite software loop/dead end. And when I try to send an email to customer support, using their form, I get some strange window that tells me that I need to use the correct email address, though I am clearly using my primary email address from my account.

Thanks, Reinhold Steinbeck