I too have faced similar issue. I believe the issue is because of Java Cloud SDK version.
Download the latest SDK from here
unzip it inside your <middleware-home>/jdeveloper directory point your cloud sdk to this new location
For example you downloaded new cloud sdk and unzipped under <middleware-home>/jdeveloper/NewCloudSDK
then point your SDK location by navigating Tools -> Preferences -> Oracle Cloud -> Java Cloud Service SDK to the above mentioned location.
Hope this helps!