because of some internal changes the plugin currently only supports freestyle and maven projects, but I'll look into this soon!

which plugin exactly you'r not able to use in the conditional-buildstep anymore? because the "copy artifact" plugin works for me (https://wiki.jenkins-ci.org/display/JENKINS/Copy+Artifact+Plugin)

Thank you for your prompt response. My note above is a little vague and inaccurate. What I meant was:

Some other plugins (e.g. "copy artifact") build steps also are missing in the dropdown list for_matrix_projects after "conditional-buildstep" ver 0.0.2 is installed

so you'r saying after installing the conditional-buildstep:0.2, you can't use the 'copy artifact' plugin in a matrix project anymore?
hmm, that's even more strange - I really see way the conditional-buildstep could cause something like this.
In the test I just made this works...
...is it the plugin I mentioned above?

I tried to reproduce the problem with blocking other plugins and could not. The experiment was not clean because since that time I deleted all plugins in my test installations and installed the latest from scratch. I stand corrected at "<blocking other build steps problem> - happened once"

I could reproduce the symptom in Notes (3) with Artifact deployer plugin.
"Note 3 in the description: Artifact deployer is not available as a build step in matrix projects when conditional step plugin is also installed"

Code changed in jenkins
User: imod
Path:
src/main/java/org/jenkinsci/plugins/conditionalbuildstep/ConditionalBuilder.java
src/main/java/org/jenkinsci/plugins/conditionalbuildstep/singlestep/SingleConditionalBuilder.java
http://jenkins-ci.org/commit/conditional-buildstep-plugin/8ef5a4c965b77ce0bbe5595ce15f7c2eee750558
Log:
[FIXED JENKINS-12036] conditional steps don't appear in matrix (multi-config) projects