I recently installed LiveCycle Designer ES4 (I had an older version before), currently a trial version (waiting for the official license key). Designer is running on VMWare Fusion 7 Pro on a Mac as there is no native Designer version to my knowledge.
Right after installation I was able to use Action Builder from Tools menu. When I opened Designer again, Action Builder was no longer available in the tools menu. Any hints to re-activate would be appreciated.
Solution: There was still a desktop alias for my old Designer 8.2.1 which I opened (and ES 8 doesn't have Action Builder). Lesson learned: Check multiple desktop items with similar names, specifically on Mac/VMWare Fusion environments.
Addendum: In the meantime I got my official license key and re-installed. Same effect: When I first started Designer (directly from installer), Action Builder men item was available. Next time when I restarted Designer, the Action Builder menu item was gone and didn't come back. So obviously not a trial version issue.