Works here on Lr 2015.10 and OS X 10.11.6
I should have mentioned that my installation is LR 2015.10 running on Windows 7 Professional 64 Bit SP1 and fully up-to-date. This could possibly make a difference.
Maybe so. I know of several glitches that are OS dependent, even the OS version. Did you restart Lightroom? Do you have any programs that redefine keystrokes? Resetting Lr Preferences sometimes helps these kinds of problems.
I don't have a key mapper and I did reboot LR. I haven't reset my preferences.
I'll wait to see if there are any replies from those on Windows platforms before doing anything further. All the other shortcuts I've tried work fine. LR in general is working fine. More curiosity than anything else.
Trying that, this particular keyboard shortcut is advertised but does nothing - Windows 10 and LR CC, both current latest versions.
"H" is, but "Ctrl+H" is not, also advertised in the menu - both of these shortcuts do work.
Your observations substantiate mine. In the context of my initial post the following seems to be true for Windows based computers (Win 7, Win 10):
H toggles between the states "Auto Show" and "Never Show" but not reliably; sometimes it toggles between the states "Always Show" and "Never Show."
Ctrl+H toggles between the states "Always Show" and "Never Show."
Shift+H toggles between the states "Show Selected" and "Never Show."
Ctrl+Shift+H appears to be non-functional in this context.
Only Ctrl+Shift+H, and H are suggested as shortcuts in the dropdown menu as you pointed out.
I think we have verified this behavior as a bug. I suppose Adobe will pick up on it at some point. I stumbled onto the anomaly after watching a tutorial on spot removal where the various selections were explained.