It seems you cannot convert Matinee’s to a Level Sequencer if the actor you have has had its scale changed in editor.
Is there any work being done to have the Sequencer converter look at the object’s initial scale set in the editor and then automatically add it to the new Level Sequence’s first key in Scale?
I’ve moved this thread to the Bug Reports section of Answerhub and was able to reproduce it with 2 different cases. I’ve entered UE-38688, where you can view the two repro cases.
Thanks for reporting this. Please be sure to report future bugs under the Bug Reports section.