Ok so I get this bug only when I dock on a POB then dock on a Planet afterward.
If I dock on a player base to drop off some cargo or just to dock and then I travel to a planet base and dock there, upon entering the commodity dealer it seems the commodities on sale at the planet are the same as those on sale in the Player Base. Then when I undock from the planet I respawn back at the Player Base.
So it is impossible to buy planet commodities and leave with them, the only way I have been able to overcome this problem is by docking with a npc base (not planet) after leaving a POB and then docking on the planet.
Seems npc bases are not bugged and by docking there first the problem is reset.
Melbourne also has the same issue, at this point SFC have givern up trying to supply it because the base where we usually get all our supplies is Manhatten ... so thats not happening anymore.
I hope this gets fixed before the rollback, otherwise I'm sure many base owners will be annoyed.