Our technical services team has informed us that the issue is due to a problem with PubMed's link resolver functionality for select articles. This isn't something we're able to fix, rather it is something that needs to be fixed on platform owner's end.
In the meantime, here are a few alternatives for access articles you are not able to access via PubMed.
Should you need assistance using any of these alternatives, please contact us through our Ask A Librarian service or email us at refdesk@mssm.edu.