The Jenkins Crowd2 plugin security plugin functionality NOT working as described (expected) in the 'Project-based Matrix Authorization Strategy':
1) Crowd group (call the group "X_TEST") given read-only permissions for all jobs in the Project-based Matrix Authorization Strategy within the jenkins application's 'Configuration Global Security' link.
2) While configuring a job (project) called "JobX_test" , I checked (true) the 'Enable project-based security' option and added the same crowd group "X_TEST" to the 'User/group' security with all job related permissions (read | discover | build | workspace | configure...etc.). Saved it.
3) Note: No other group is enabled within the project ("JobX_test").
4) User "X" who is part of the "X_TEST" group only logs in and can NOT configure (nor build) the job ("jobX_test").
5) IF I increase the overall group's ("X_TEST") permissions to build and configure in the application's 'Configuration Global Security' link, THEN the user can build or configure the job ("JobX_test")!

So, bottom line, application permissions overrides the individual 'project-based security' permissions! It should be the opposite functionality in which individual 'project' permissions supercedes the applications's security settigns for the group (or user) as described in the following link:
https://wiki.jenkins-ci.org/display/JENKINS/2012/01/03/Allow+access+to+specific+projects+for+Users(Assigning+security+for+projects+in+Jenkins)