Custom snap areas disappeared when docking

Describe the bug
After undocking and then reconnecting my 2017 MBP (macOS 10.15.6) to my CalDigit USB-C hub, custom snap areas disappear from my external monitor - sometimes, after several hours of being undocked. Using same USB-C port to connect.

Diff dx: I've tried to reproduce just now by creating a new custom area on laptop monitor & external monitor, and then...

  • undock then dock = no symptoms
  • undock, put to sleep, dock = no symptoms

Affected input device (e.g. MacBook Trackpad, Magic Mouse/Trackpad, Touch Bar, etc.):
External monitor

If applicable, add screenshots to help explain your problem. (You can just paste or drag them here)

Device information:

  • Type of Mac: MBP 2017
  • macOS version: 10.15.6
  • BetterTouchTool version: 1.9.3