It is just beyond me that Apple can not resolve this issue. My Siri voices on my mac delete themselves. I reported this to Accessibility Team and have received the traditional reply of sending my issue out to the specialized team for further investigation.
Again, I suspect there is an accessibility team, and i do doubt that Apple really cares about accessibility anymore.
Now for those who would come up and say they do not have this issue with their macs, OK congratulations, it happens on mine, and I paid for my mac as you did, if it is not an issue for you, honestly I do not care, I care for the money that I paid for a device I expect to work the way I want.
Rant over! Good day, and merry christmas for all.