Image Convert Grayscale block breaks workflow

Adding an image convert grayscale block to a workflow produces the error: For image given as np.ndarray expected 1 or 3 channels, got 390 channels. It appears that the number of channels directly equals the width of the image predictions by the dynamic crop block above:

{
“image”: {
“width”: 1466,
“height”: 1955
},
“predictions”: [
{
“width”: 390,
“height”: 405,
“x”: 747,
“y”: 1316.5,
“confidence”: 0.9611872434616089,
“class_id”: 0,
“class”: “Dice”,
“detection_id”: “f019d614-2a2d-41ab-ace5-5cde32f6d5e5”,
“parent_id”: “image_convert_grayscale_image”
}
]
}