Blackrock Ore, for example, is “stuck” and you cannot purchase even one from the lowest price (currently standing at 1 silver, normal price around 52s). There was a similar issue at the start of DragonFlight. From memory this was caused by bot accounts repeatedly posting and cancelling 1 of an item at a ridiculously low price, over and over and over again, hoping to catch out unwary sellers. The item in question had to be manually deleted to “unstick” it.
(Edit: note I’ve already reported this in-game on my EU account)