To put it simply, the Add New Key button does not function within the Actor Sequence Editor and it appears that the Sequence Editor is completely unattached to the Viewport Editor. In addition, following the steps below, you can observe an additional error when attempting to use the Viewport editor to drag the X coordinate of the Cube Mesh that results in the Sequence Editor coloring the text name of our “Cube” red and a mouseover will sometimes notify that the object reference is broken (mouseover does not appear to consistently work).
These are the steps I used to reproduce this issue in the simplest possible form.
- Create a new blank project
- Enable Actor Sequence Editor plugin and reload project
- Create new Actor Blueprint
- Add Cube Static Mesh Component to DefaultSceneRoot
- Add Actor Sequence Component
- Click Sequence → Open in Tab
- In Sequencer, use + Track to add our Cube Component to the timeline
- + Track in Cube and select Transform
- Use the “Add a new key at current time” + button
- In Components, select Cube Component and set X location of Transform to 100
- Use the “Add a new key at current time” + button
Following these steps, you can observe that in the Sequencer Timeline, the location of the Cube Component is not set to the Transform of the Cube Component within the viewport.
In addition, it then becomes impossible to drag transform(s) of the Cube in the Viewport, only resulting in the transform being set to bizarre location values.