Music not in order (Purchased List) Ipod 7th

Can anyone tell me what is happening Itunes player and ipod are both up to date but recently new music once moved to Ipod 7th gen Purchased List is not in the same order as before .They are now appearing at the very end of Purchased List when they should be the first i see on the list of Purchased. Sync does nothing does deleting the entire list of Purchased music from Ipod 7th and syncing again correct this issue and how do i go about it ? also can the Purchased list be long as i want given enough storage on the device is left ? Thanks