Hi. I’ve got exactly the same issue.
Angry Earth at eternal pool only drop 9 out of 16 Protective Resin needed for the Resin-Hardened Leather. After you get the 9 resin, the quest switches to using the tannery.
Resetting the quest does nothing, because you already have the 9 resin the quest wants to give you.
Character Name: Teranos
Server/World: Aaru
When did it happen?: 16.12.2022 6:30 a.m. (German Timezone)
Bugged for me on Avalon. Did finish the quest though by doing the following. Only collect 8 of the items. Then go and kill enough mobs to complete and leave quests item loot on ground. Once there is enough on ground pick them up so you have 16 in inventory. Below is a clip of me doing so showing I have 16 in my inventory and was able to complete after this.