I don't think you have missed anything other than generally speaking programs written for Windows 7 no longer work on Windows 10. I do not know what the settings available for your program are like as I don't use that program so I could be wrong. Do you know what what version of windows it was written for? That info is normally in the programs' pdf manual.
Microsoft Windows 7 (32/64 bits), Microsoft Windows Vista (32/64 bits), Microsoft Windows XP (32/64 bits), Windows 8 (32/64 bits)
Most Magix software after 2015 were Windows 10 compatible.
I also discovered, This PC program was developed to work on Windows XP, Windows Vista, Windows 7, Windows 8 or Windows 10 and can function on 32-bit systems. The most popular version among the software users is 13.0.
The current latest version of PS Deluxe is 20.0.1.62. Your version 13.0.5.94 is thus seven full versions behind. I think it was therefore released quite some time before 2014!
.Some MTS files require a Dolby audio codec which is no longer part of Windows 10. My understanding is that this codec can be downloaded, if needed, to later versions of the program but this option is not possible, it seems, with your version.
You may be able to convert the audio of the video file to a format which PS 13 can use by running it through a convertor, like the free Handbrake.
To date I have only found audio programs that will run in compatibility mode in Windows 10 that stop working and Photoshop CS6 although that could change for the worse as Windows continually evolves. Every now and then after a windows update I have to go around and reset those programs that have stopped working providing they allow certain audio aspects of the program to be changed. Compatibility mode as I understand it only seems to deal with colour and resolution aspects of the programs but I'm not sure. At least the help section only seems to hint at that. For instance, dragging a work area across two screens when each screen is connected to a different graphics card.
Thanks Ray for the in depth information, yes I noticed the articles on colour and resolution, I suppose it's always something to check out or even try it out, based on the users needs, before ultimately looking at a software upgrade, cheers. 👍