I wonder, can I perhaps turn on some verbose logging? I'd like to compare log snippets on a machine where it works well with a machine where it doesn't work...
In your SQL Developer installation's sqldeveloper\sqldeveloper\bin directory you will find...
3. Note that sdcli.conf starts with IncludeConfFile sqldeveloper.conf
4. Note that debug mode is enabled in sqldeveloper.conf by changing the line
So switching from non-debug to debug could possibly provide you with some extra information.
As to what might be the problem, the only thing that comes to mind is to ask which Java (JDK) version is used (if any) on the CI machine? Depending on the Bamboo release in use, it might be using Java 1.6 or 1.7. Does Bamboo require a JDK like SQL Developer, or can it get by with just the Java JRE? The latest SQL Developer requires JDK 1.8.0_40, but that version check does not seem to occur in SDCLI, and for all I know some code might need the newer JDK.
Hope this helps.
since locale is pretty much the only difference between the working and nonworking machine, I wanted to try switching from German to English, and yes, after switching to US English (adding the following lines to sqldeveloper\sqldeveloper\bin\sqldeveloper.conf)
The whole thing started to work! Thanks for the suggestion! This is a really nasty bug, if you ask me...