Arduino IDE 1.8.12 (and 13) crashes under macOS with eGPU

Using a late 2018 MacBook Pro under Catalina with an eGPU, Arduino IDE 1.8.12 (and a nightly build of 1.8.13) crashes pretty well immediately (and certainly as soon as I touch it). If I sleep the eGPU and do evertything on the laptop's own screen then it works. If I then restart the eGPU, the Arduino IDE starts crashing again.