The PubmedImportMetadataSourceServiceImpl and associated classes (used by the XMLUIStartSubmissionLookupStep, see https://wiki.duraspace.org/display/DSDOC6x/2016+Framework+for+live+import+from+external+sources#id-2016Frameworkforliveimportfromexternalsources-PubMedIntegration) uses a deprecated http:// endpoint. The respective server responds with "301 - Moved permanently" and refers to the https:// endpoint. This causes the SubmissionLookupStep to fail without any user feedback. In 6.2 the SubmissionLookupStep is an optional feature that has to be activated by an administrator.
The PubMed endpoints are present in the current 6.2 release as well as the 7.0 master branch. In my dev environment I could resolve the bug by changing all endpoints that started with http://eutils.ncbi.nlm.nih.gov/entrez/eutils/ to https://eutils.ncbi.nlm.nih.gov/entrez/eutils/. The files affected by this are