my friend https://imgur.com/a/cbctUxy
mine: https://i.imgur.com/NAhLnjD.png (currently on alt with buffs)
we've been in same party, died together etc etc. Tried turning on guild sync still doesn't update.
Other guild / party members also can't get his table
(missing about 2500 from the pool?)

It does not update instantly like on privateservers. On a pool difference of that size it will compare each of your both entries one by one and add the missing players in your poolsize step by step.

This was due to the bug with week reset. Sync is woring reliable, old data is just discarded for one guy and saved for another.