The Thor in High Impact Payload mode plays a wrong animation when you are using the Tyrador skin as the model is missing the correct animations.
The Collector’s edition’s animation file has the missing animations.
These can be added in the editor’s model tab like this:
<CModel id="Thor_Silver">
<RequiredAnimsEx FilePath="Assets\Units\Terran\ThorCE_SwarmAnims\ThorCE_SwarmAnims.m3a">
<Flags index="Override" value="1"/>
</RequiredAnimsEx>
</CModel>
Now the Tyrador Thor has a similar attack animation in High Impact Payload Mode.
Documentation & Test Map: github.com/Ahli/sc2xml/issues/5
Video demonstrating the issue and the fix: StarCraft II - Fix Attack animation of Thor using Tyrador skin in High Impact Payload Mode - YouTube