[GAMEPLAY] Shopping Bug ,item sells out automatically

I bought the Banner and waited for another $1200 for buying Raptor Cloak. But I found out the Banner disappeared, it has sold out by itself.

1. buy the banner ( 1st item )
2. change the item spot
3. buy the cloak ( 2nd item )
4. the banner disappeared and sold by itself.

So not sure why that happened, but I can say it's not the first time. Maybe happened around 5~6 times. I always thought I had miss clicked, but by watching VOD. I can say that's a bug.