Twilio integration - certificate import fails Error 5203

I'm trying to get Twilio integration to work with SSPR as the SMS provider has changed. I've looked at GeoffC and KarlaB's discussions, as well as the support and training video at: but I'm getting an error of:

Error 5203
Configuration format error: %1%

5203 CONFIG_FORMAT_ERROR (error importing certificates: null)
So, I took at look on the appliance and the error log gives" FATAL, servlet.AbstractPwmServlet, {27462} unexpected error: 5034 ERROR_INVALID_FORMID (form nonce incorrect)"

Any ideas?