Pro-Ject Pre Box S2 Digital slow in changing formats

The last couple of days I noticed that the Pro-Ject Pre Box S2 Digital is slow in changing formats, e.g. from no MQA to MQA playback: the MQA/MQB indicator does not show and the sample rate indicator does not change.
The Pre Box S2 only reacts after turning the volume dial or pushing some buttons, e.g. the filter button.
My Pre Box S2 is directly attached via USB to my NUC running ROCK.
Rebooting did not change the behaviour.