Any new here? having same problem when trying to create index patterns containing remote clusters. Indexes are being found but then fails to list fields in next step with same errors described above.
User has full permissions on both cluster and index level. Can it be that some of these operations are being done by kibanaserver user? What exact permissions then needed to list fields?
Also same user can make API calls and read desired indexes on remote cluster.
Using OD 1.13.1 version