ASIO routing issue when soloing individual channels

Windows 10, RME HDSP MADI, SL 11 … all latest drivers and versions.

I’ve just installed the upgrade to SL 11, so please bear with me if this is a known issue (… forum search didn’t show any related threads, though).

I have a perfectly working 5.1.4 (or actually Auro 10.1) output routing when I start playback, but as soon as I solo one of the channels, the audio is routed to all (!) channels offered by the ASIO driver, which is quite a lot on a RME MADI card. 8-/ … needless to say, the result is unusable.

There are no obvious errors in SL’s Preferences. I’ve also tried various options in the Prefs without success. Any suggestions?

TIA!