Non-Food Recipes
By default WP Recipe Maker adds recipe metadata to all of its recipes. According to Google’s guidelines this is only allowed for food recipes, however. We also have metadata for how-to instructions, but not everything is covered by that either.
If you want to use the plugin any of those other non-food and non-how-to recipes you need to make sure that metadata is not there by selecting “Other (no metadata)” as the recipe type when editing a recipe:

The plugin will not output any JSON-LD metadata in that case, making sure you’re in line with Google’s guidelines.