Shop bug (Rakan?)

So i was playing support full AP, and i was doing the , then i started to build , i built the 3 "sub-items" (and when it came to buy the full item, i couldn't, the item was grey like i had not enough gold, it was saying the item cost was 865 when it should have been 450), i just couldn't buy it.

I sold my 850 explosive staff, and then i was able to purchase it at a normal cost (but i lost golds from selling an item i needed) and then, same thing with , so i decided to dc and when i came back, everything was fine.

Is it a known bug atm ? Is it only on AP items ? Only on Rakan ? I've heard of bugs on the supp items, but the supp item was the only item i was able to purchase normally with the magic pene boots that i one shotted.