It's not possible to access a metafield via liquid if it contains a "/" character in the key name. This is due to the fact that the "/" character is treated as a path separator in Liquid and is not valid in variable names. It's recommended to avoid using special characters like "/" in metafield keys to ensure compatibility with all parts of Shopify's system, including Liquid.
You may need to rename your metafield key to something without the "/" character to be able to access it via Liquid. For example, you might change "A/C" to "AC" or "A_C". Then you would access it via Liquid, eg: