That was funny
But what's really funny is that "Check for Updates" has only displayed updates for Third Party stuff for many, many consecutive releases now.
And note that the release notes (SQL Developer Releases Notes 18.2) state:
Installing or Upgrading
- All new releases of SQL Developer require a full installation. Download and unzip the file into an empty folder. Ensure the "Use folder names" checkbox is checked when unzipping the file.
So, effectively, you should not expect "Check for Updates" to work until the release notes in a future release announce it.
Never expected that 'Check for Updates' really update SQL Developer. Wanted only information about available update displayed after SQL Developer opening.
So it works but is dead as feature :-)