To activate cascade particle first time on sequencer is not work in a specific way.

The bIsActive flag on ParticleComponent is stored in a sequencer asset.
If it's true, PartilceSystemComponent::ActivateSystem is skipped at FParticleTrackExecutionToken::Execute.

In workaround, Setting the "Trigger" state at first frame instead the "Activate" state.
The "Trigger" forces to activate it whether it is true or not.

1. Open the attached project  [Link Removed]
2. Open NewLevelSeqeunce
3. Move the particle component location to make it dirty. (It's important)
4. Save the sequencer asset (with pausing state and set cursor location at start).
5. Play in PIE

Result:

The particle is not displayed at a first loop.