Exactly which Magix program and version do you have? The screen you show is not the normal Export screen from either Video de Luxe/Magix Movie Studio/Movie Edit Pro or Video Pro X.
Can you hear the audio when previewing the video in the project , if not:
Is the audio track muted as shown below?
Can you see the audio as shown above, you may need to select the video clips and press Ctrl + H. If not then we need more information about the imported video to help diagnose the issue(s) you are having:
Download and install MediaInfo and analyse one of the clips and post the results, see this tutorial on how to setup MediaInfo and analyse a video clip for all the data required.
Unfortunately the forum uploader converts your videos so those won't really represent your files. Could you please put one of your problem files onto Google Drive, Dropbox or similar and post the link here so we can analyse it.
It appears from your first post that you import onto the timeline with "video/audio on one track". Is it possible that you have right clicked the clip and under "Audio functions" you have accidentally clicked "Mute audio object"?
If so, even after pressing Ctrl H the audio will still be muted but there is no indication that it's muted - at least in MS2025 there isn't.
Thank you for the sample files. I do see that these files are the original .MTS files from your Panasonic camera, however you posted, and is shown in your image in this comment, that you have a file with the .MP4 file extension.
Did you change the file extension from .MTS to .MP4?
No AC3 decoder should be required, as @Bol has commented the update 23.0.1.236 should fix the issue.
With Video Deluxe 2026, the new name for Movie Edit Pro / Movie Studio, the audio is heard when played from the Media Pool.
As a double check I tested with an older version of Movie Studio, Movie Edit Pro 2016, which does not have the Dolby AC3 decoder installed, no audio is heard when played from the Media Pool, however on importing to the timeline the audio is heard when played from the timeline.