I just set up a Scala project in Eclipse (Oxygen 4.7.3a, on Ubuntu 18.04) with the Scala-IDE plugin (4.7.0.v-2_12-201709291352-71a28d0) with a simple HelloWorld object. If I set "Properties -> Scala Compiler" to 2.12 everything works as expected: the project compiles and runs. But if I choose any other version (for instance, "Latest 2.10 bundle (dynamic)" I get prompted to do a full rebuild (as expected) but when I go to "Project -> Build" nothing happens. If I have errors in my code, the editor underlines them, but they won't show in "Problems". If I try to run it I get a class not found error.
I get the feeling that it is not actually compiling. Any ideas on what I need to configure differently?