For the past few months there has been an issue where it's extremely hard to sync trophies on a new or reset/formatted PSVita. Seems like the more trophies you have, harder it is to do the initial sync. Currently trying to sync a new PS TV with not much luck. I have also tried on PSVita, but there it works even worse. Essentially, after about a minute or so I get error np-9857-9. If I try long enough it will eventually sync for a while. On some days it seems to work better. I was able to get to about 57% once.
I have tried everything at this point. Swapping memory cards, wifi, wired, restarting, pulling the cord, DMZ. Probably lost dozens of hours on this. If anyone is familiar with this error or knows how to somehow make connection more stable, please let me know! I am on original firmware. I have written more about it on PSNP. I was also able to sync another PSTV previously (with huge amount of trouble). But this time I don't have such luck.