By Sunspot
#208613 I've had this same issue, too. It's always big nuggets given as quest rewards that seem to be bugged and refuse to be sold. They won't stack with other big nuggets, either. From my own experience, this is actually a common bug that seems to effect a majority of stackable quest rewards.

Gold ingots, diamonds, potions, almost anything I get from quests won't stack and won't sell in shops. However, if the bugged items are part of a crafting recipe, they will work normally when used in those recipes.
User avatar
By SauskeHigurashi
#209863 I don't exactly know why these items aren't appearing under the sell tab in shops, but I do have an idea on whats probably going on. Each of these quest items are gaining an NTB tag for whatever reason. I think the NTB tags are probably used to separate the quest items from your current items maybe. This could possibly be an intentional thing to show the new items so you don't get confused, or the Pixelmon Reforged team could possibly have just goofed up on this one. Either way, I don't exactly know the truth behind it.