Models are kind of finicky because of how Roblox implements them. There really isn’t a location property on models, so your only option to move the model is to set the WorldPivot.
However, if you don’t use PrimaryPart, it should work as expected. This is because if a PrimaryPart is set, the WorldPivot is automatically set, which may or may not break your animation. For this reason, I might remove PrimaryPart from the animatable properties. Is there a reason you’re using PrimaryPart in your animation?
Ah, unfortunately, that is a bug that you can’t do anything about. If you have an old save file, you can probably get your progress back that way. Fortunately, it should not happen again once you update the plugin.
Again, I’m so sorry that this happened! I know how jarring it is to lose progress. I went through extensive testing to try to catch critical bugs. But alas, I’m just one developer and can’t catch everything. I’m very grateful that you’re going out of your way to report these to me!