Host "" is already a member of VDS DSwitch

Hi All,

I'm having an issue adding an ESXI 6 host to a vSphere Dist Switch. It keeps coming up with the error Host "xx" is already a member of VDS DSwitch. It isn't as far as I can see anywhere attached to it, the first time I added it had an issue where it couldn't connect to the host and then after that I removed it and tried again and now getting this issue.

Thanks

Ryan