Why are some products only available in one size?

I have just uploaded a new design for this product:
… but to my consternation it is only possible to buy it in size 4XL. While I am absolutely against people starving and not have enough to eat, I DO think they at least should be able to buy a tshirt which will fit them. So… why is it only possible to buy this tshirt in size 4XL? Is it a supply issue? Will the other sizes come back some time?..

Hi @FrameMaker Unfortunately, we actually had a supply bottleneck with the premium shirts.

This shirt in particular is available in many sizes and we are very sorry that there were no smaller sizes for a while.

At the moment, however, most sizes in most colours are back and we are busy stocking up for the Christmas season!