Changing the covariance matrix could work.
Adding the date parameter is probably the clean way to solve issue 1697, but it requires modifying the library.
Could you check very fast it it solve the issue for you?
There is a vote ongoing for publishing version 13.0, if you can confirm very fast it work, we could probably interrupt the vote and merge the fix in this version, or we could just let the vote conclude and publish a patch version (13.0.1) very soon after, or we could just put the fix in develop and wait for 13.1 if you can use develop on your side even before 13.1 publication.