Slnc Commands not working with macOS Sequoia

Brand new Macbook Pro 14, M4, Sequoia 15.1

I have a number of 'Notes' which I regularly get the Macbook to read to me. I have successfully used the '[[slnc 1000]]' command to make it pause for 1 second between each sentence on my Macbook Pro 16 (2019) for many years, but the upgrade to Sequoia 15.1 has broken it... The Macbook now reads out 'slnc 1000' instead of pausing for 1000ms (1sec).

The issue seems to be with Sequoia.

An old Macbook 12 running Ventura 13.71 works correctly and pauses for 1 second.

Is there a fix for this very annoying problem?

[Re-Titled by Moderator]