MaaS360 extender - web service invalid response

Getting this error from the extender log:

INFO MaaS360WebService:193 - Initializing MaaS360 Web Service …
INFO MaaS360WebService:198 - Web Service is Configured …
DEBUG MaaS360WebService:209 - API retries on HTTP failure: 3
DEBUG MaaS360WebService:211 - API retry interval is: 10 seconds
DEBUG MaaS360WebService:217 - API Page size is: 250
DEBUG MaaS360WebService:295 - Sending request to Web Service …/auth-apis/auth/1.0/authenticate/20006435/
ERROR Utils:194 - Element type “meta” must be followed by either attribute specifications, “>” or “/>”.
ERROR MaaS360WebService:337 - Invalid Response from MaaS360.org.xml.sax.SAXParseException: Element type “meta” must be followed by either attribute specifications, “>” or “/>”.
— rest of stack trace removed —
ERROR MaaS360WebService:254 - Authentication Failed.
ERROR Plugin:115 - Could not authenticate with Web Service

This is the first time a connection has been attempted to the MaaS360 service from IEM/BigFix.
It is a SaaS implementation, so the root url I am using is https://m2.maas360.com/.
I can use the same credentials to log into the MaaS360 site via the browser (successfully).

Hello,

The root url for the MaaS360 Management Extender is often not the same as the portal. For example, we use https://portal.fiberlink.com to access the portal, but the root url for our Management Extender, for web services, is at https://services.fiberlink.com.

Can you verify with MaaS360 that you have the correct root url for web services?