As @AleksiAlkio said you need to have them in the column definition.
About the images, if you still want to use them :
If you want to have images in the enum, you have to add them in the “suggested values” of your column and set the base type as Image.
Suggested values formula would look like : list(concatenate(dim0%), concatenate(dim50%),concatenate(dim100%) )
I suggested Dynamic but if your bug only happen because of progress type column, it don’t need to be dynamic at all, it can be a normal svg or images from your drive.
Example of what your enum suggested values formula can be :
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list(CONCATENATE("data:image/svg+xml;utf8, "),
CONCATENATE("data:image/svg+xml;utf8, "),
CONCATENATE("data:image/svg+xml;utf8, ")
)
*replace the numbers in bold to edit values
*to make it smaller just make a request with chatgpt 
It should return like this in your form :
If you want to use your own images, which may be easier, put them in your drive and set them as public, then instead of list(dim1,2,3..) , use list(“driveexportURL1”, “url2”,“url3”). You can convert your files url to export using this tool : https://sites.google.com/site/gdocs2direct/
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Then you may want to create a new column to capture the current progress where if(progress=url1 (or dim1) value , then 0%, if(progress=url2 (or dim2), then 50% , if (etc) ) )
Hope it helps !