I don’t think this is actually documented anywhere, but it is something that you will want to be aware of if you are using the BPM 11.1.1.5 Feature Pack.
It is not supported to install the Feature Pack patch into an Oracle Home which contains JDeveloper and the runtime components (WebLogic, SOA, BPM, etc.)
If you are installing on the same machine, like a developer’s machine for example, you should install JDeveloper into a separate Oracle (Middleware) Home.
Building a Custom BPM Worklist, Oracle InSync 2011 User Group presentation
Performance Tuning for Oracle Business Process Management Suite 10g, Oracle Whitepaper, July 2011
Performance Tuning for Oracle Business Process Management Suite 11g, Oracle Whitepaper, February 2013
Oracle BPM Suite 11g: Advanced BPMN Topics, Packt Publishing, September 2012
Fusion Middleware 12.1.2: Developing Applications with Continuous Integration
Fusion Middleware 12.1.3: Developing Applications with Continuous Integration
RedStack 
Good post – I ran into the same issue. Took weeks to figure out what I’d done to cause the FP not to install. Sure this will be a big help to others. The error you get when you do this is “Patch 12319055 requires component(s) that are not installed in OracleHome. These not-installed components are oracle.sysman.plugin.ai.main.oms:11.1.1.5.0”.