Thank you for your message.
I've checked with our developers once again - perhaps, the issue occurs specifically with this beta version release of the macOS. However, we will make sure to test the Viewer for Mac compatibility with the macOS beta version to see if there are any issues that we can fix in our subsequent updates.
Meanwhile, you might try running the Viewer from a stable macOS version (for example, Mojave or Catalina), if possible.
Sorry for the inconvenience. I'll get back to you if there are any updates on the issue.