We are also having a problem with the Flexible publish plugin on matrix jobs. The checkbox does not exist in the "Post-build Actions"

I tried copying the xml code from a regular job and update the config.xml of the matrix job and it worked. The problem is that every time someone is configuring the matrix job and hit save it removes the Flexible publish section since it does not exist in the UI.

Fix will be really appreciated.

Yes please...

Flexible Publish for multiconfiguration projects are disabled with code:

        public boolean isApplicable(final Class<? extends AbstractProject> aClass) {
            //@TODO enable for matrix builds - requires aggregation
//            return FreeStyleProject.class.equals(aClass);
            return !MatrixProject.class.equals(aClass) && !PROMOTION_JOB_TYPE.equals(aClass.getCanonicalName());
        }

@bap
Let me know the case using Flexible Publish in a multiconfiguration project causes a problem. That is the case that requires an aggregation. I'll consider a way to resolve.

Flexible Publish must support MatrixAggregatable for work with multiconfiguration projects.
This allows publishers work both for each axe combination builds and the parent build.

Sent a pull request.
https://github.com/jenkinsci/flexible-publish-plugin/pull/2

Code changed in jenkins
User: ikedam
Path:
src/main/java/org/jenkins_ci/plugins/flexible_publish/ConditionalMatrixAggregator.java
src/main/java/org/jenkins_ci/plugins/flexible_publish/ConditionalPublisher.java
src/main/java/org/jenkins_ci/plugins/flexible_publish/FlexibleMatrixAggregator.java
src/main/java/org/jenkins_ci/plugins/flexible_publish/FlexiblePublisher.java
src/main/java/org/jenkins_ci/plugins/flexible_publish/MarkPerformedBuilder.java
src/main/resources/org/jenkins_ci/plugins/flexible_publish/ConditionalPublisher/config.jelly
src/main/resources/org/jenkins_ci/plugins/flexible_publish/ConditionalPublisher/config.properties
src/main/resources/org/jenkins_ci/plugins/flexible_publish/ConditionalPublisher/help-configuredAggregation.html
http://jenkins-ci.org/commit/flexible-publish-plugin/3fbb375fed52cc506e7493a6542d967bcf846af3
Log:
JENKINS-14494 Supports MatrixAggregator.

Code changed in jenkins
User: ikedam
Path:
src/main/java/org/jenkins_ci/plugins/flexible_publish/ConditionalPublisher.java
http://jenkins-ci.org/commit/flexible-publish-plugin/22d147c19a151d1942a4f5d6dc3bf252b2a775a1
Log:
JENKINS-14494 compatibility of the constructor of ConditionalPublisher.

Code changed in jenkins
User: ikedam
Path:
src/main/java/org/jenkins_ci/plugins/flexible_publish/ConditionalPublisher.java
src/main/resources/org/jenkins_ci/plugins/flexible_publish/ConditionalPublisher/config.jelly
http://jenkins-ci.org/commit/flexible-publish-plugin/99e2d375f166e1e1ff02a40f74d08bf354380e71
Log:
JENKINS-14494 use ${it} instead of Stapler.getCurrentRequest().findAncestorObject()

Code changed in jenkins
User: ikedam
Path:
src/main/java/org/jenkins_ci/plugins/flexible_publish/FlexiblePublisher.java
src/test/java/org/jenkins_ci/plugins/flexible_publish/AggregationRecorder.java
src/test/java/org/jenkins_ci/plugins/flexible_publish/MatrixAggregationTest.java
http://jenkins-ci.org/commit/flexible-publish-plugin/d172222f1b743581acb1ca8c899616bddde1f31f
Log:
[FIX JENKINS-14494] Tests for Matrix Support.

Code changed in jenkins
User: ikedam
Path:
src/main/java/org/jenkins_ci/plugins/flexible_publish/ConditionalPublisher.java
src/main/java/org/jenkins_ci/plugins/flexible_publish/FlexiblePublisher.java
http://jenkins-ci.org/commit/flexible-publish-plugin/4b03cee2f35acac2018237871495cb49897908ea
Log:
JENKINS-14494 Removed unnecessary imports.

Code changed in jenkins
User: ikedam
Path:
pom.xml
http://jenkins-ci.org/commit/flexible-publish-plugin/6b8fb4023efc2b50f456bd53f914ca95813db4ff
Log:
JENKINS-14494 Make compilable with JDK 1.7.

I added this feature in flexible-publish-0.11.
Please try, and report issues if something wrong.

Jenkins LTS 1.532.1
Flexible publisher plugin 0.12
Jenkins Subversion Tagging Plugin 1.16

I have a matrix job with 2 labels and the flexible publisher as post build action.
I checked the check butten "Condition for matrix aggregation", set "Run on parent?" to "Always" and set "Perform subversion tagging on successful build" as action.

Result: The matrix parent job performs no tagging! The parent jobs console output even shows no output from the flexible publisher plugin.

Originally I hoped the new matrix support will solve this problem: https://issues.jenkins-ci.org/browse/JENKINS-9683

Subversion Tagging Plugin does not support running on matrix parents.
Even without Flexible Publisher plugin, your job should not run as expected.
Flexible Publisher plugin does not make a publisher who does not support matrix projects support them.

Anyway, Create a new ticket.