Hello, Martijntje,
Thank you for contacting us and for using XStore.
Why do you use the old theme version v.8.0.7 https://prnt.sc/E-tHlGMUUrh5 , but the updated Core plugin?
You need to update the theme – https://www.8theme.com/documentation/xstore/theme-installation/theme-update/
Please do not update the Core plugin before the theme update.
Kind Regards,
8theme team