Cannot filter using the isValidIp function in CloudWatch

Hi

I'm currently experiencing issues when trying to use the "isValidIp" function for filtering logs in CloudWatch

fields @timestamp, StatusCode, RequestPath, @@m, isValidIp(Host),!(isValidIp(Host))
| filter !(isValidIp(Host))

I expect the query above to filter all logs where "Host" is not a valid IP address, but nothing is being filtered. At the same time, I render isValidIp(Host) and !(isValidIp(Host)) and see that these can clearly render the correct values for the function.

Is there some limitation or is my syntax incorrect?

Here is a link to a screenshot of the query and results: https://ibb.co/NSM8qM3