This is a report of a Lightroom CC 2015 problem after upgrading to El Capitan 10.11.2 on an iMac early 2009 with 8Gb of memory, 2.66 GHz Core 2 Duo, GeForce 9400 256 Mb memory. Problem is in Develop module, whether "Use Graphics Processor" is checked or unchecked. An image in the Develop module is about 2 stops darker than the same image in either Library or Print Module. Attempted edits in this darker Develop module do not carry over into the Library or Print Modules. Also, adjustment brush is surrounded with a brighter square and does not work normally. Activating "Soft Proofing" restores the Develop module, and after creating a virtual copy, Develop module seems to function normally, though on a "Proof" copy. Since this computer was a late adopter of El Capitan, I can report that no problems existed under Yosemite. And, LIghtroom CC 2015 1.1 Develop module functioned properly in the early version of El Capitan, before 10.11.2. A second computer, a Mac Pro Early 2009, 2.93 GHz quad Core Xenon, 32 Gb memory, Nvidia GeForce GT 120 512 memory does not exhibit this strange Develop module behavior. To reiterate, it appears that LR functioned with no Develop module problems until the El Capitan 10.11.2 update. Rolling back to LR 2015.1.1 shows this Develop module behavior even though before El Capitan 10.11.2 there was no such problem.