Hi there
You may wish to try duplicating the slide and editing the new
slide to see if it removes the artifact.
Other than that, when recording you have a couple of options.
1. You don't see the countdown unless you are also recording
audio at the same time. That's not an optimal setup. Many folks
choose to add audio later as a separate process. Perhaps consider a
change to your workflow for a more professional result.
2. If you choose to continue this workflow, just note that
this artifact is likely going to be present and factor it in. Wait
until you are certain it's gone before commencing with your
recording.
Whatever you choose you should report to Adobe as a bug as it
shouldn't be happening.
Click
here to view the WishForm/Bug Reporting Form
Cheers... Rick