Businesses & Hobbies Pack Unable to Sell Large Items

I see that we can sell any item that fits on the designated units under the small business build tab. I am trying to create a music store to sell guitars and violins. I can't put these items on the 'Ankle Biter Pedestal? There's plenty of space on it.  Same for the Cube of Wood Retail Display. Guitars come with the pack, but we can't sell them? I opened a shop and was able to sell gnomes. But I can't sell guitars or violins? Would love for this to be fixed.