Yes you are right, I also used those options. I edited my previous answer accordingly.
Unfortunately I can't give you an answer directly out of my knowledge what you need to do now, but for TWRP I also found out that it is possibly an encryption issue.
- Use an external microsd card to read the zip from there
- Wipe Data in recovery
- use "adb sideload" in recovery
Wiping data of course erases all of your data.
I will see what I can do and follow your tips.
Thank you for your time and your effort to help me!