No, it is not “fixed”.
Real fix would require using actual demand for price calculation AND ability to sell certain amount of commodity. Along with much faster recalculation of demand amount.
Naturally, it will cost both development time and increased server load.
Therefore, instead of real fix FD made an imitation of it. Breaking functionality of 3 rd-party tools in the process. There is no point to gather market prices if those prices are different for every CMDR.
In theory, it may become a good solution. IF (and only if) that price would be calculated on amount you “shown to buyer”, not your entire cargo hold.
For example you have mission to “mine 75 tons of palladium”. You have 150t in your cargo, and planning to sell excess. Then why price is calculated from your entire cargo hold?