It looks like my Ultimo can only use one of its three tuners with OpenVix 5.0.021 or 5.0.023.
First I noticed an error message about not finding service a few days after I had updated to 5.0.021, when there was a timer recording going on and I turned on the tv and the receiver. (Don't remember the exact words, and I have Finnish set as the interface language. And I'm not sure whether or not this was the first time with 5.0.021 that the box should have shown one channel when another one was being recorded.) It turned out to only be able to show the channels in the same group as the one being recorded. After the recording had finished, all the channels were visible again.
First I tried to search the tv channels again, which took a long time and didn't help. Then I tried flashing 5.0.021, restoring the settings, and that didn't help either. When I flashed back to 5.0.020, everything seemed fine.
Yesterday I updated to 5.0.023 (with online update), and in the night when there was another recording going on, the same thing happened, I wasn't able to see the channels that would have needed using another tuner. In the morning I tried some of the channels that couldn't be shown when the recording was going on, and they were fine again.
So I assume that for some reason OpenVix versions newer than 5.0.020 can't use more than one of the tuners.
No logs to send have been created.
When I go back home from work, I will probably flash back to 5.0.020 again.