Same issue here. Noticed it first thing this morning. It's 530pm now and same issue. Can connect fine if there's no password. But with a password, I just get the error about the password field being blank.
On xbox, the text won't populate (so the password field really is blank).
Trying on the Windows 10 version, it SEEMS to populate the password (you see asterisks), but when you try and load, you get the same blank password error.
Edit: Tried joining a random server with no password. Looks like ALL in game text input is broken too. Not just passwords. So likely an Ark issue, not Nitrado. Annoying.