To reproduce:

1. In a new project, create a cube
2. Select the cube and press Ctrl + Alt + 0 to save the selection (the selection is saved)
3. Try pressing Ctrl + Shift + 0 to load the selection (the selection doesn't load)
4. Select the cube and press Ctrl + Alt + 6 to save the selection (the selection is now not saved)
5. Press F2 to rename the cube, then Ctrl + Alt + 6 to save the selection (the selection is now saved) and pressing Ctrl + Shift + 6 will load the selection

Expected: the hotkeys for saving/loading selection should work as they are supposed to
Actual: sometimes hotkeys do not work until the respective menu item is pressed, some hotkeys do not work at all

Reproduced in 2017.2.3p2, 2017.3.2f1, 2017.4.7f1, 2018.1.6f1, 2018.2.0f2, 2018.3.0a5

Not reproducible:
Advanced Keyboard Settings -> Language Bar Options -> Advanced Key Settings and set Between Input Languages to None for both, then Apply, Ctrl+Shift+0 and other selection hotkeys will work perfectly.