Please see my post above and advise which part do I copy and paste into the "signature" field when signing up.
If you signed segwit this worked for some people:
Insert this
-----BEGIN SIGNATURE----- your legacy address your signature -----END BITCOIN SIGNED MES
or
-----BEGIN BITCOIN SIGNED MESSAGE----- BitCoinRhodium_xxx -----BEGIN SIGNATURE----- your legacy address your signature -----END BITCOIN SIGNED MES
(yes, with MES at the end)
Still not getting through, error message below:
Your signature or voucher are invalid. Try it again or contact our support.