Hi matousekconsulti,
Thanks for reaching out to us here. Welcome! Categorizing your transactions in QuickBooks Online, is an essential step in preparing to reconcile your accounts. I can understand your concern, when you're unable to categorize your expenses effortlessly. I would be glad to assist!
Initially, I recommend that you uninstall, then reinstall the app. If the issue persists, I recommend contacting our Customer Care team outside of this forum. They'll have the ability to review the issue in more depth, and escalate it for further investigation with our Development Team. In addition, they'll set you up for an email notification when the issue has been resolved.
Please don't hesitate to reach back out, if you have any other questions or concerns. We would be happy to help!