shirts with only one size

Hello
Spreadshirt offer some products with only one size to order.
For example: Girlieshirt only available in XL.
In your PlugIn you can choose all sizes for this product.
Order wrong size ends in “nothing happen” when put in basket.

Is there any way to fix this problem? (get the real sizes from spreadshirt in dropdown)
test it on: https://immershop.de/

Another question:
Is it possible to get the own created categories in the cat. dropdown on top?

By the way… Great work!

https://www.ads-software.com/extend/plugins/wp-spreadplugin/