Since the app is now notarised you can't inject frameworks anymore and debug it inside Xcode.
I've made an example project to try out:
After some Googling I found this:
Not sure this would solve it though.
@maximedegreve disabling SIP worked for me (of course it's not the safest way since you disabling system level protection this way).
PS: instruction is here: https://www.macworld.com/article/2986118/how-to-modify-system-integrity-protection-in-el-capitan.html
That worked @dannyow . Thanks for that! How did you even find this out, this kept me busy the whole day yesterday.
Glad I could help. Catalina, codesigning and hardened runtime kept me busy lately (e.g. see my other discussion re framework signing for 10.15).