Thanks for letting us know about your experience with the "receipts" feature in QuickBooks Online, @katharina-scheck.
I can share some updates on why this is happening on your end. We recently received reports from customers who are unable to snap and upload receipts in the program. This problem has been escalated and it is now under investigation. Our engineers are currently reviewing this issue to implement the solution.
We currently can't provide the exact turnaround time on when this will be resolved. We instead send live updates about the status of the investigation through email. If your email is not yet added to the notification list, I recommend contacting our support. You can contact us directly to be added to the list of affected users and receive real-time updates about the issue.
Provide the investigation numbers INV-77226 or INV-77302 to our agents. Here's how to contact us:
Go to the (?) Help menu, then select the Search tab.
At the bottom, select Contact us.
Enter the keyword Account Management and Billing in the What can we help you with? box.
On the next screen, scroll down to the Choose a way to connect with us section.
Choose Chat with us to initiate a discussion with a live agent.