Custom ACF block only outputs commented JSON to the DOM

I created several custom ACF blocks and all but one are working properly. This one in particular only outputs commented out JSON to the DOM.

Here’s what it’s displaying (with a few string values removed to keep the client anonymous).

<!-- wp:acf/button {
    "id": "block_60dba85ef281c",
    "name": "acf/button",
    "data": {
        "button_background": "purple",
        "_button_background": "field_6061da93a6d15",
        "button_text": "",
        "_button_text": "field_606227d36073e",
        "button_link_target": {
            "title": "",
            "url": "https:///",
            "target": ""
        "_button_link_target": "field_6061dc177bf40",
        "open_in_new_tab": "0",
        "_open_in_new_tab": "field_6061dc7d1fa44",
        "block_background": "purple",
        "_block_background": "field_606a59f7086ae",
        "button_alignment": "center",
        "_button_alignment": "field_606a5a8a98021"
    "align": "",
    "mode": "preview"
} /-->

I registered this block in register_acf_block_types() the same way I registered all the other blocks and verified the template file exists and doesn’t have any errors. It just displays a simple styled anchor tag.

One thing I noticed is the "mode": "preview" line at the end. But this block has been published.

I’d appreciate any insight on this. Not quite sure where to look at this point.