Frontend editor wont show up at all after installation. Tried to set it up like an other project where it works, but the error constantly shows up.

Error console log: Uncaught SyntaxError: Unexpected identifier engine.js?0808dd08ad62f5774e5f045e2ce6d08b:61 Uncaught ReferenceError: addonsJSON is not defined at Object.<anonymous> (engine.js?0808dd08ad62f5774e5f045e2ce6d08b:61) at t (engine.js?0808dd08ad62f5774e5f045e2ce6d08b:1) at Object.<anonymous> (engine.js?0808dd08ad62f5774e5f045e2ce6d08b:61) at t (engine.js?0808dd08ad62f5774e5f045e2ce6d08b:1) at Object.<anonymous> (engine.js?0808dd08ad62f5774e5f045e2ce6d08b:30) at t (engine.js?0808dd08ad62f5774e5f045e2ce6d08b:1) at Object.<anonymous> (engine.js?0808dd08ad62f5774e5f045e2ce6d08b:30) at t (engine.js?0808dd08ad62f5774e5f045e2ce6d08b:1) at engine.js?0808dd08ad62f5774e5f045e2ce6d08b:1 at engine.js?0808dd08ad62f5774e5f045e2ce6d08b:1

I already checked the FAQ recommandations (cache, gzip compression, php 7.4 is working fine on an other SP PageBuilder project of mine, etc.)