Time: Anytime
Frequency: Roughly once ever 2-4 hours of gameplay
World name: Lamia
Character name: Cleo Haven
NPC name: none
Monster name: none
Class/Level: All
Party or solo: All
In-game time: Anytime
Area and coordinates: Everywhere
Steps:
1. "Hotbar 2 - Slot 11" is assigned to [`]
2. "Character" is assigned to [\]
3. After a few hours of gameplay, the hotkey assignments for both "Hotbar 2 - Slot 11" and "Character" will suddenly dissipate, and either one of them will be instead assigned to [']. Note that both hotkey slots will malfunction at the same exact time.

Screenshots:

There appears to be a difference between a "dissipated" hotkey assignment, rather than an unassigned hotkey.

Example of "Dissipated Hotkey"
Notice how the brackets are next to the skill name but does not actually have an assigned hotkey.



Example of "Unassigned Hotkey"
A skill that is not assigned to any hotkey will not have brackets next to it's name, which suggests that the first example is a bug.



Example of a skill randomly being assigned to [']
When both hotkeys malfunction, only one of them is assigned to ['].



This is strange because the default assignment for this hotkey is [Ctrl+-]. So why [']?