If you solo'd that quest you had to have been a much higher level. Quests "gray out" (give negligible amounts of XP) when you level too far beyond them.
This. If you were well above the level range, you won't get anything for completely quests, even the Elite ones.
I had a guildmate who out-leveled the Elite quests on Coruscant, went back to do them (in his high teens for a few) and didn't get any rewards for it.