When using an Oxygen 25/49/61/88 (blue) with DirectLink in Cubase, it is not possible to select a different bank of tracks by clicking on screen with the mouse.  The Track < and > buttons must be used to select a track within the next or previous bank of 8 tracks.  Clicking to select a different track on screen will cause a disconnect with the selected track and currently selected group of tracks under control.  To switch banks after clicking a different track on screen, you must use the Track < and > buttons to select one of the tracks current under control, and then navigate to select a track within the desired bank.

For example, if tracks 1-8 are currently under control, and you click to select track 24, in order to gain control over tracks 17-24, you must use the Track < button to select Track 8, then use the Track > button to select track 17.