In LR5-times the shortcut for show/hide filter... (don't know the eng. translation) was "<" now you look to the menu and find "/"
But / does not work. If you look into the LR help they write "shift-/", but you only change color to yellow, like with normal "7"
but if you click "alt-shift-7" it works.
In LR5 I just had to click on "<" now I have a monster short-cut.
This is really no progress,
Which version of LR, which language, and Mac or Windows?
LR 6 now LR 2015, OSX.10, German
See this bug report in the official Adobe feedback forum, which includes a workaround: LIGHTROOM 6 - Filter bar keyboard shortcut does not work on German keyboard. Please add your vote and opinion to make it more likely Adobe will prioritize a fix. If you reply or follow that report, you'll be notified of any fixes and workarounds.