The hotkey only works to close the mod panels, not to open them

[RayDurand]

The hotkey set in the mod's options panel only works to close the panels, not to open them. Changing the hotkey from the in-game configuration doesn't fix the issue.
Expected behaviour: the hotkey should work to both open and close the mod's panels.

Log:
KSP.log

Running KSP.x86_64 version 1.9.1.2788, resolution 1920x1080
OS: Manjaro Linux with XFCE
Mod version: 1.1.6.1, downloaded from CKAN