Click File->Export -> Export Geckolib Display Settings, and there is no reaction. More specifically, there is no window popup.
Try reinstall plugin & blockbench also do not work.

Blockbench Version: 4.0.5
Plugin Version: 3.0.1
System: Win 10
GeckoLib Model Setting: Block/Item
Saving Model Project as: .bbmodel (converted)

Related with #196

Additional Info, console of blockbench app:

Maybe related with this line at the plugin repo

Posible problems:

• Fetching unexisting metadata from .bbmodel file

Export models as .geo.json works fine.

Solved at the geckolib Discord here. Thanks