MySQL Error: This version of MySQL doesn't yet support 'IGNORE NULLS'

Question

I am trying to join two tables on the product_id and date columns. The product_date_cross table contains all date and product_id combinations within a time range. The review data is only available for specific days. In order to fill the missing values of the average rating, I wish to populate the last available non-null value. I am trying to run the following query on MySQL database:

SELECT 
    pdc.productId AS product_id,
    pdc.selected_date AS date,
    rd.avg_rating,
    COALESCE(
        rd.standing_review_count, 
        MAX(rd.standing_review_count) 
        OVER (PARTITION BY pdc.productId  ORDER BY pdc.selected_date  ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW),
        0
    )
    AS review_count,
    COALESCE(
        rd.standing_avg_rating , 
        LAST_VALUE (rd.standing_avg_rating) IGNORE NULLS
        OVER (PARTITION BY pdc.productId  ORDER BY pdc.selected_date  ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW),
        -1
    )
    AS avg_rating
FROM product_date_cross pdc
LEFT JOIN review_data rd
ON ((pdc.productId = rd.productId) AND (pdc.selected_date = rd.review_date))
ORDER BY pdc.productId, pdc.selected_date

Everything is working fine except for the LAST_VALUE part. When I try using the IGNORE NULLS clause I get the following error:

SQL Error [1235] [42000]: This version of MySQL doesn't yet support 'IGNORE NULLS'

I checked the MySQL 8 documentation which suggests that this is the correct syntax for LAST_VALUE.

Is my query missing something? Or is there another way of getting the last populated average rating?