After clicking on the X button to delete the image, you need to submit the changes to update the field value. If you reload the page and click again, the error will show up because the image has been deleted completely.
Regarding the thumbnail does not show up, I will inform the development team to support this in future updates.
After clicking on the X button to delete the image, you need to submit the changes to update the field value. >>> I know, i tried as you said, but it does not delete the image if i use Custom upload folder
Please upload new images and re-check this issue. You can also take a look at this screen record https://share.getcloudapp.com/p9ukOgO5
and let me know if it is your case.
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