1. White Orchard region at the cemetery north where the Igni Place of Power is at. There is a wraith, somehow seems bugged for me. Hit it a couple of times then it disappeared. I proceed to the crypt and the metal gate locked me in and the wraith appeared again, unfortunately it happily ignored me, unlocked the gate and walked out. Thats the last i see of the wraith, it was at half life and i didn't get to kill it. Tried waiting for the different timings 12mn, 12am etc etc, but the goddamn wraith don't spawn anymore. Bug?

2. White Orchard again, Southwest of Nilfgaardian Garrison, the guarded treasure icon on the map. Checked guides, supposed to have water hags defending. Went there, no mobs at all, no bodies/corpses even and i was free to loot the chest. So technically an unguarded treasure. Bug?

3. Beast of White Orchard quest, supposed to visit Tomira to for the buckthorn which i've settled that but the Milvas part where i'm supposed to look for the Hunter and save him from the wolves was 'skipped' and left out of the quest objectives. MIssing extra exp, mini quest there. Bug?

1. That's how that wraith is. Whether by design or not I don't know.
2. The drowners and the water hag are roamers; they don't stay next to the loot all of the time. The hag sometimes dissapears (underwater?)
3. You must ask the commandant at the Nilfgaardian garrison about both Tomira and Mislav (not Milvas), when gathering information about the Griffin, for them both to initiate in the quest log.

Thx for the reply. I tried searching for the water hags on the entire map of white orchard, but can't find them too. My bestiary codex for them remain empty. Do they have some conditions to spawn like noonwraiths etc?

For Mislav, i've already done what you mentioned, spoke to the commandant who directed me to Tomira and Mislav but only Tomira's objective marker and Griffin's Nest objective marker lit up. There was no 'mini quest' for Mislav. Still managed to complete the quest though. I've tried loading an earlier save before but same outcome, there is always no objective for Mislav. I've also visited him and lo' n' behold he is sitting outside his house cleaning his bow instead of out in the woods getting gangbanged by wolves. He don't trigger any conversation too.

I don't know if the hag has a spawn condition. All I know is that sometimes I have found her and sometimes not.

I don't think you actually miss any XP by not talking to Mislav, who doesn't give you any information that you can't discover yourself, anyway. I'm not sure why he doesn't get activated for you, though.