Not sure if this was the cause or not, but we have recently setup the SEC_USER_UNAUTHORIZED_ACCESS_BANNER in the sqlnet.ora file to display a login message. We only did this on node 1. I did remove it; however, I kept seeing the message. What I ended up doing is bouncing the instance, and that resolved it and Sql Developer is now also working. Again, not sure if simply bouncing the instance would have resolved this, but these are the steps I took.
Searching this forum's content tab for BANNER, I see a similar case where the poster was able to get DB connectivity working even with the security banner enabled:
The solution then was to use an OCI/Thick JDBC connection in conjunction with a JDBC driver appropriate for SQL Developer 4.x.