Based on the screenshot, it looks like a known issue with Navigate 1.5, that was fixed in Navigate version 1.5.2. Here is the KCS article that outlines this issue. Hope this helps!
As mentioned by Bibek this is a known issue in Navigate 1.5.0 and is fixed in Navigate 1.5.2. Refer CS269109 for details of this issue.
To confirm this issue is same as the one mentioned in the article, check for this error message in ThingWorx Application logs : Thing [AttributeSelectorThing] is not running]
[context: com.thingworx.webservices.context.HttpExecutionContext@19c618f8][message: Unable To Parse JSON Request]
Exception executing service, GetDisplayableAttributes, on resource provider: WindchillDemoPartResourceProvider
[context: com.thingworx.webservices.context.HttpExecutionContext@c076d05][message: Unable to Invoke Service GetDisplayableAttributes on PartsListAccessAppThing : JSON Server error HTTP 404 ]
Are you able to search for objects in Navigate? If not, Windchill is not yet connected to ThingWorx/ Navigate.
This looks to be a configuration issue and not the product issue mentioned above. Please open a TS case for investigating this further. Make sure to attach the Application logs and Method server logs.
We also had come across a similar issue. The problem we had was the attributes doesn't show up but the windchill connector showed positive connection and even the services were working. Then we checked the baseURL of the connector. We had given small letters in the hostname. Even though the URL worked, some services were not invoking properly. So it seems that the base url was case sensitive. After changing it to the proper case letters the attributes become visible to us. Hope this helps.