Not saving non-english custom attribute images

Hello,

I purchased and installed the plugin while having some products with their own custom variations already setup.
I created a custom filter and tried to add images in the said fields. When I click on the save attributes button the images are cleared.

After some testing I realized that if I change the filter and the custom attribute field name to english (instead of the default language which is Greek) the images in those specific attributes are saved as they should. The only way to save those images is if I directly click on publish instead of first saving them. This causes a problem because each time I might want to add or change something the variation images are lost.

Are you aware of that issue? Is there any way we can resolve this?