Under macOS 10.14.6, a Mac mini is compatible with a Breakaway Box with Vega 56, Vega 64, WX 8200, and WX 9100. A Mac mini with a Breakaway Box with an RX 560/570/580/590 must be booted with a monitor connected to the Mac mini’s HDMI port. The monitor may be moved to the GPU after booting. This anomaly is fixed in macOS 10.15.7+.
Do you have an Intel®-based MacBook Air®, MacBook Pro®, Mac mini®, iMac® or iMac Pro with Thunderbolt™ 3 ports? If you need to run pro editing, rendering, color grading, animating, and special effects apps, you need a graphics processing (GPU) power boost.