I am trying to add a new DKIM TXT record as advised by Zoho support to try and fix a long standing DKIM issue with my account. 

When I add the new record it shows up in checks, but does not pass.  Using the tool linked in the DKIM creation page on Zoho this error is shown:

This doesn't seem to be a valid RSA public key: RSA.xs:178: OpenSSL error: too long at blib/lib/Crypt/OpenSSL/RSA.pm (autosplit into blib/lib/auto/Crypt/OpenSSL/RSA/new_public_key.al) line 91.

Other DKIM checkers show the DKIM as being invalid etc.

Has anyone been able to resolve this?  It looks like a server issue to me.  

Some extra info - I use Cloudflare for my DNS.