Android App - File upload not possible

Hi,

I have an issue with the Android App.
If I try to add a file (in this case a PDF <1MB), I can select the file, but if I click on ‘Select’ Cryptomator close the vault automatically and nothing is uploaded.

I use Cryptomator with Linux and Windows. No issues so far.

Do I need to do somthing different?
I’m using the latest Version of the Android App and read files from the vault is no problem.