Explorer2 USB DAC not recognised as MQA device

When connected, the Explorer2 USB DAC is not recognised as an MQA device, though I have switched on “Auto-detect MQA devices”. I have to set “DAC not detected as MQA, use as” “MQA Decoder” to make the DAC’s blue MQA LED to lit up when playing MQA files. I use Audirvana 3.5.21 on a MacBook Pro running Mac OS 10.14.6. The DAC is connected via an USB-C to USB adapter.