From experience, this is due to formatting errors when writing the lore:
to make a gradient/colored text bold for example, the format has to be <b><#color>asasasa</color></b>, and not <#color><b>asasasa</b></color> for example
The bold / italic / etc formatting characters must always be applied on an already colored text, else it'll break when the lore is updated (so when you get a kill, when you put it on the market, etc)
The permanent owner tag from /trade is a bug iirc