Invalid connection credentials SharePoint in Standard Gateway

Hi all, 

All our previously working connections to SharePoint in the standard gateway are throwing an "invalid connection credentials" error and won't let us re-authenticate.

I've reached out to MS support and honestly not getting anywhere. Feel I'm getting a generic response that you don't need a gateway for SharePoint etc. and that we don't use it for Cloud sources. I've asked them to confirm if the SharePoint connection type in the gateway has been decomissioned but not really getting anywhere with that.

We use the gateway for SharePoint as it provides control on who has access to create dataflows against certain sites etc. 

Any idea, 

1) If the SharePoint connection type in the standard gateway has been decomissioned?
2) If anyone knows a fix or what could be going wrong.  The VM hosting the gateway can log into SharePoint so dosen't seem to be a firewall/networking issue.