There is an issue with channel:form, it is deleting data it should not. The following channel entry form will delete all grid entries I have for product_images. The grid_entry field is product_images, and there are two columns called image and image_alt.
Yet using this code (notice I am not editing the grid field product_images that is being deleted), the grid field will be blank after saving, and no other field will be affected, just this grid field used for images.
{exp:channel:form channel="products" return="product" entry_id="801" include_jquery="no" include_assets="no"}
<input type="submit" name="submit" value="Save">
{/exp:channel:form}
I have other grid fields for the entry that are not deleted, and I have a File field that is not deleted. So its either something to do with this specific field, or to do with the Grid field that has a File field in it.
Using EE 2.7.2
