This was reported in BuildAndDeploy forum https://groups.google.com/a/genexus.com/forum/#!msg/buildanddeploy/mFdIsnRLQKE/MJjUrFD8AQAJ

There's also a similar issue about git-client-plugin at https://issues.jenkins-ci.org/browse/JENKINS-32712 

When a project uses SCM polling, if the polling fails (eg: bad credentials) although the plugin throws an exception, the engine takes that as "no changes", the build is not triggered and it's hard to note the problem.