This happens to you when using the pre flight events when the time reaches 0?
Normally you'd call for the "Before Start checklist" well before the time reaching 0.
Then you'd run the "below the line" portion of the checklist at around time 0.
You can cancel any checklist by speaking, I recall "Cancel Checklist".
Then you could call for the intended checklist again.
Also, with Flows, using the "manual flow selector", you can manually trigger any Flow you like at basically almost anytime.
But it happens to you again, be sure to look at the Log in the Info Center. It will tell you what the speech system actually heard.
Maybe the system though you said "After Start Checklist" inadvertently? Only the log will say.
But let me know. If there is something we can tweak or polish, we'd like to know so we can address it.