We recently found that when a creative (or any other version of metadata) is removed by a user within the LinkedIn Ads user interface, LinkedIn also removes that creative from the data that we receive from the API. Our append/replace logic that was in place to prevent duplication in the datasets prior to 2023-07-23 happened to be doing a full replace on the data, meaning that all data in the table was deleted and then replaced every day by the newest version of the data that we could get from the API. That means that we weren't retaining any creatives if they were no longer being provided by the API. On 2023-07-23, we changed this append/replace logic to retain any creatives that we have received previously, but are no longer being provided by the API.
This all means that you should no longer encounter this issue going forward, but, unfortunately, we are unable to pull any historical creative metadata from the API. If LinkedIn Ads creatives are missing in your data, please open a ticket with Platform Support and provide a file that contains the creative ID and name, at a minimum.