There are a number of steps you can take if you experience playback issues or artifacts when using Pro Tools Ultimate and the Dolby Audio Bridge:
 
Depending on the complexity of the session (track count, plug-ins, automation), you may need to disable extra processing (re-renders, binaural, loudness) in the Dolby Atmos Renderer preferences, as well as any unused outputs (speaker and headphone) during mastering. You can also disable video playback in Pro Tools during mastering.
 
In the Pro Tools Playback Engine window, ensure that “Ignore Errors During Playback/Record” is disabled during mastering. It may be enabled while editing, but if it is, ensure that “Minimize Additional I/O Latency” is unchecked, as this will induce 6101 errors regardless of system usage.

6101 errors may also occur when using a 2nd monitor on some laptops. This has been known to occur using a 2nd monitor with a  MacBook Pro 2019 (2.6ghz 6 core i7, 32gb ram)

Note that Dolby Audio Bridge v2.0 and Renderer 3.7 remove the need for aggregate devices. If you have previously created aggregate devices to fix playback errors you will need to delete them when you install the new Dolby Audio Bridge and Renderer.