PrestaBay supports differents way to support ebay variation products.
1st way.

It's send PrestaShop product with combination to ebay with variation option. For enabling this possibility it needs to activate option on Selling Profile -> Product tab

2nd way

Send each PrestaShop product combination as a separate product to ebay. "Variation" option on Selling Profile should be disabled but on Selling list required to enable "Combination" option. 

This look like this
1st -
2nd - select product from PrestaShop -
3rd - you have selling list with each combination
4th - result of list item

3rd way
Send PrestaShop product with combinations as a single ebay listing without an options (variation). You need disable "Variation" option on Selling Profile -> Product tab.  Also, does not enable "Combination" option on Selling List.