Problems with 3.4.3 and building an IntelliJ Plugin

Hey MPS-Community,

I tried to build an IntelliJ Plugin with MPS so I can use my Language in the IntelliJ Idea.
I followed all the steps in https://confluence.jetbrains.com/display/MPSD32/Building+IntelliJ+IDEA+language+plugins and got a lot of Errors from javac like this:

[javac] Compiling 171 source files to ....\ProjektarbeitGit\CFMLang\build\tmp\Project2\java.modules.cycle.1
[javac] .....\ProjektarbeitGit\CFMLang\languages\ExpressionLang\source_gen\ExpressionLang\editor\WriteInEmptyLine.java:12: error: cannot find symbol
[javac] import jetbrains.mps.lang.editor.menus.substitute.ConstraintsFilteringSubstituteMenuPartDecorator;
[javac] ^
[javac] symbol: class ConstraintsFilteringSubstituteMenuPartDecorator
[javac] location: package jetbrains.mps.lang.editor.menus.substitute
[javac].....\ProjektarbeitGit\CFMLang\languages\ExpressionLang\source_gen\ExpressionLang\editor\constants.java:12: error: cannot find symbol
[javac] import jetbrains.mps.lang.editor.menus.substitute.ConstraintsFilteringSubstituteMenuPartDecorator;
[javac] ^
[javac] symbol: class ConstraintsFilteringSubstituteMenuPartDecorator
[javac] location: package jetbrains.mps.lang.editor.menus.substitute
[javac] .....\ProjektarbeitGit\CFMLang\languages\ExpressionLang\source_gen\ExpressionLang\editor\rebuildAst.java:12: error: cannot find symbol
[javac] import jetbrains.mps.lang.editor.menus.substitute.ConstraintsFilteringSubstituteMenuPartDecorator;

Because I couldn't figure out what was wrong (Nor Error Messages from MPS before), I downgraded to MPS 3.4.1 and it worked without any Problems and I was able to use my Plugin.

Anybody an idea what could be wrong?

Best Regards

Kai Meinhard