Invalid ViewContent value parameter

Hi,

While using this plugin to connect to Facebook, we are seeing this issue on Facebook, regarding the pixel events:

Issue: Invalid ViewContent value parameter
One or more of your ViewContent events has invalid characters in the value field. This may affect your ability to see return on ad spend calculations.

Solution: Check source code
Open your website’s source code. Locate the ViewContent event(s) and update the event code snippet. The value field must contain a decimal number greater than zero, and may not include letters, special characters, currency symbols or commas.

The products in question are products that are not currently available, so do not have a price. The pixel code generated by this plugin has this as the value:

fbq('track', 'ViewContent', {
    "source": "woocommerce",
    "version": "4.2.2",
    "pluginVersion": "1.11.4",
    "content_name": "ATP Noway Collagen Bar",
    "content_ids": "[\"wc_post_id_158285\"]",
    "content_type": "product",
    "value": "",
    "currency": "USD"
});

Judging by the error message, this either needs to be 0.00, or omitted entirely.

Any help would be much appreciated.