When I launch InDesign CC (2015.2 Release, 18.104.22.168 build) the Control panel appears. If I close the file or close the InDesign window, the control panel disappears and won't come back even though it is checked off under "Window". The only way I can get it back is to Quit InDesign and relaunch. Interestingly, if I open a second file and then close the first file, the Control panel will remain visible. Anyone else having this issue?
What operating system are you running?