The problem is caused by line 301:
if (this.dontShowFeature('effectList', stateObj)) return html``;
If you rework it like this:
let effect_list = stateObj.attributes.effect_list || [];
// if we were given a custom list then use that
if (this.config.effects_list && Array.isArray(this.config.effects_list)) {
effect_list = this.config.effects_list;
} else if (this.config.effects_list && this.hass.states[this.config.effects_list]) {
// else if given an input_select entity use that as effect list
const inputSelect = this.hass.states[this.config.effects_list];
effect_list = (inputSelect.attributes && inputSelect.attributes.options) || [];
} else if (this.dontShowFeature('effectList', stateObj)) {
return html``;
}
it should work