Hello Josef Rosner,
Thank you for reaching out to our technical support forum. I’m sorry to hear about the trouble you’re experiencing. Rest assured, I will look into this issue for you and work to resolve it as quickly as possible.
I have checked your issue in Opera browser on mac. It works fine. On right mouse click, context menu opens perfectly. Please check your browser version. If not updated, then update it to the latest version.
Sorry, Internet Explorer browser is not supported. Use Microsoft Edge browser instead of it.
Best regards