Shift8: "custom key" support

From the forum, it seems the "custom key" support doesn't seem to function correctly:

Any chance to get the “custom key” implemented as well? I installed the SHIFT-Actions App from their F-Droid Repo an can configure the key but it none of the actions get triggered by a key press.

https://community.iode.tech/t/the-shift8-is-now-officially-supported-and-in-stock/7071/4?u=rik