Case closed, thread can be closed.

Not a Kodi or MPV issue. It's DRM related.

2. Yeah I guessed as much. Thanks.

If anyone has any experience with Kodi and MPV, please let me know what I am doing wrong.

I know the Kodi part is going through, when I click on an Add-On like Optus Sports or Foxtel GO (streaming services in Australia) and play a live channel that would work normally with Kodi's internal player. It says:

External Player Active
Click "OK" when playback has ended.

So I am assuming MPV should be taking over from that point, after I click on the channel. But it's not opening at all, regardless of whether SVP is open or not.

Is there an extra add-on I need to install for Kodi? Or perhaps change something in the settings?

Also took out my personal MPV configuration file, so that MPV runs stock. Same thing, so it's not any configuration that's causing the issue.

1. there's no "official MPV"
2. no difference

Here is what I am using for Kodi configuration in user data:

<playercorefactory>
    <players>
        <player name="MPV" type="ExternalPlayer" audio="false" video="true">
            <filename>C:\Program Files (x86)\SVP 4\mpv64\mpv.exe</filename>
            <args>-fs "{1}"</args>
            <hidexbmc>false</hidexbmc>
            <hideconsole>false</hideconsole>
            <warpcursor>none</warpcursor>
        </player>
    </players>
    <rules action="prepend">
        <rule video="true" player="MPV"/>
    </rules>
</playercorefactory>

I would appreciate any feedback, thank you.