unable to mount NETCONF node with deviation against ietf-netconf-monitoring

I'm unable to mount a device which has a deviation against ietf-netconf-monitoring:

<hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<capabilities>
<capability>urn:ietf:params:netconf:base:1.1</capability>
<capability>urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring?deviation=cisco-xr-netconf-monitoring-deviations</capability>
<capability>urn:ietf:params:netconf:capability:candidate:1.0</capability>
<capability>urn:ietf:params:netconf:capability:rollback-on-error:1.0</capability>
<capability>urn:ietf:params:netconf:capability:validate:1.1</capability>
<capability>urn:ietf:params:netconf:capability:confirmed-commit:1.1</capability>
...

no models are being loaded to the cache.

ODL appears to think the device doesn't support ietf-netconf-monitoring as I see this log:

"Netconf monitoring not supported on device, cannot detect provided schemas"

I'm not sure if this is strictly a yangtools bug or a netconf bug.