Should be fixed now
Sure, which items aren't buying?
It checks the items you already have before going to GE, it won't buy anything if you already have everything it requires but this includes teleport tabs and enchanted jewelry for some quests. There is a special iron man mode in development if you press F5 on the GUI which will automatically gather the required items for a few quests. You can also see what items it's missing if you open the logger on top right corner of the client under settings, it will print a list of items it attempts to buy before going to GE.