Unable to buy items in item sets in the shop

​I was playing as Blitzcrank (don't think that matters) and was fooling around with an item set and I found that when I would try to build items that were in the item set, they could not be built, even if I selected them through the shop. There were two main occasions during the game where this happened: the first was when I had Aegis of the Legion and Glacial Shroud, and had 2300+ gold. With that pair of items it would cost me 250g to combine them into Zeke's Convergence, but for some reason I was completely locked out from combining the items, even while dead or at the spawn fountain. I also couldn't purchase other items that I would have been able to buy, such as Locket. I did end up taking a screenshot of this, but the moment I entered the shop to take the screenshot it became available for me to buy- I did end up getting a screenshot of the second occasion (during this same game). The second occasion was slightly later in the game, I had a Needlessly Large Rod, preparing to build Spellbinder, and had 1974 gold, but could not purchase the item, even though I was dead. I couldn't purchase it when I came alive either, I even backed to base several times and could not combine the Rod with the gold for the rest of the game. I think it might be linked to the item set I had of these items, as I had made the item set just before this game and had never had this problem before. Also, I did try purchasing the items both in my custom set, and in the normal shop.