Dynamic Material Instance changes not visible in rendered movie or PIE

Using this technique here to keyframe my Material Instance parameters in Sequencer>
"In Sequencer you add your object then click [+ Track] > Materials (choose slot here) and then for this material [+ Parameter] and choose parameter. "

Works fine when I scrub back and forth in the Sequencer. ie a simple custom ‘Emissive Intensity’ parameter that I’ve keyframed.

However when I Render out a movie or playback in PIE mode the changes are missing!
Is the only solution to change Material Instance parameters via the Level Blueprint?

see