Etsy marked my item No Longer Available in that color?!

[CreeksideCraftwork]

What would cause Etsy to tell my buyer that an item they had in their cart for several days is suddenly "no longer available" in the color she wanted? I haven't had any sales on that item, and I haven't touched the listing since I posted it.

Thankfully, she placed the order anyway (for a different color), and asked if I could make at least part of it in the color she wanted. If she hadn't asked, I would never have known there was a problem. It makes me wonder if that's why my similar item isn't selling, even though it's in several carts.

What gives? Why would Etsy tell my customers that my posted item is no longer available?

[ArtDollsbyJD]

It's possible the buyer was using an old version of the app?

I had no problems with the colors from the items that have colors for selecting.

[CreeksideCraftwork]

I guess it is possible. Do you think it would have anything to do with the fact that the item sat in her cart for a few days? She said she didn't see any errors in the listing today, or on the day she put it in her cart, only when she actually checked out.