Cannot get Selkie Veil from the chest

[Geralt]

I got here with the guy missing form the monastery, the chest is glowing but there is no prompt to open it. Only "Disarm lightning mine" which I did - did not help, now there is no prompt. Brother Eagan stands there with huge question mark. I exhausted all dialog - does not help.

[LordDeimosIV]

Try exiting the dungeon entirely and then go back in. It might reset the chest and allow you to loot it. I completed the quest with no issues but I've read threads where some people ran into the issue you're talking about.

[Sassa]

It tend to happen if you raid the cave before you get the ques. that was the issue in OG as well IIRC.