Switch to the Confluence skin for now. Once we get it working there, we can head back to your preferred skin if you prefer and modify it.
Open Kodi/XBMC
System
Appearance
Skin Confluence Customizable Mod (click it please)
Confluence
Confirm Skin Change
Press the home icon, bottom right of TV
Scroll left to Pictures menu, and from your post it sounds like you know what you're doing from there.
Main issue here is that music, videos and pictures are distinct areas in the app. Once above works OK, you can head to
System
Appearance
Skin Confluence (click it please)
Confluence Customizable Mod
Confirm Skin Change
Settings (just below that Skin link you clicked)
Submenu items
Find an area and specific entry you're happy to lose, and click on it.
Select Pictures Window
Give it a name
Click Done
Return to XBMC's homescreen and the newly edited menu should now link to Pictures, as it did in Confluence.