Originally Posted by
ilcannone
Thankfully I don't have to book them, my employer takes responsibility for that, but I'm also not sure what you mean about the components of the fare(s)?
I should have mentioned before that it was all in economy in the lowest fare category for each sector.
There are multiple fares available within each class of service. Some would allow minimum stay at destination of 7 days, others would only work if you stay beyond Sunday of the week, etc. Some fares simply cannot be combined.
For example, when you combine multiple flights on one PNR, if your first leg has only a flexible Y fare available, all remaining segments will need to be "combinable" (i.e. within same flexible fare bucket), even if a lower fare is available. This is most likely the case here. This is probably also aggravated by availability of SU's "Far East" fares for OW tickets. Russian government subsidizes some of the flights to the Russian Far East, but these fares are only available for simple return or one-way tickets.
Finally, SU web-site is also a bit glitchy, which may also be a contributing factor.