There is a bug in Photoshop CC2015 for PC. The healing tool does not work on separate channels. For example, the tool gives a "program error" when used only in the Red Channel. The tool gives no error message in Blue and Green channels, but has no visible effect either. Under composite RGB mode, it seems to work (usually), although it works more poorly than CC2014, giving anomalous effects when trying to heal speckled areas. This bug has been confirmed with Adobe Technical Support on-line chat.