Mind you that being said Astra was near enough the same (but in a different position in the sky - Astra at 19.2 degrees East compared to Thor which was 5 degrees East) which may have had more to do with it (Astra may also have had longer solar wings too), but all satellites were at risk of sun outages:
This is different to a sun outage, they occur twice a year around the autumn and spring equinox and are when the sun is directly behind the satellite and overwhelms the signal into the dish. You get a brief decrease in signal from the satellite.
The Superchannel example is different, the outage is power related and as Trish says they will happen every night for a few weeks.
Presumably its to do with being out of view of the sun and thus without power. Though why the batteries wouldn't keep not going I don't know. Maybe Direct to Home services like Superchannel were higher powered and thus shut down to preserve the lower powered communications ones?
Here is how Dish TV in the US handled sun outages in the 90s. Note, this is the signal into them degrading, not the one to the customers dish... hence they were able to put up a caption about it