I have a Facebook commerce catalog set up that adds and updates products via pixel. I need to add some optional data fields for the products, i.e. gender. According to Facebook documentation, the name of the OpenGraph tag for gender is product:gender and its supported values are Female, Male, Unisex. However, adding this tag to the product pages of my website doesn't seem to work. Facebook's microdata debugger is also not capturing it.

I wanted to know what is the correct meta tag syntax for adding the gender property. Currently I have the tag written as follows:

<meta property="product:gender" content={get_gender()} />

Other OpenGraph tags such as material and color also doesn't seem to be added. Can anyone help me to get this working?