1. In the OS Mio setup (post #21), do the options for "Channel: SatCR 2" start at SatCR0 or SatCR1?
If starting with SatCR0, change your setting from SatCR2, for 1420 Mhz, to SatCR1 and leave 1420 as it is.
Does that bring life again to the OS Mio?
2. Now you have the OSMio set to Unicable/JESS/dCSS/aCSS/a²CSS, your other receiver should be working with the OSMio on, as it did before while the OSMio was OFF. Does it do that?
If not, disable the motor settings on the Mio, and tell us if that improves things.
(Not for the permanent solution, but for the testing.)
3. With all these changes, if needed try to switch off both receivers completely (disconnect power cables), to be sure that the LNB was without power and can reset. Then switch ON again, and test again if things work.
Greetz,
A33