Driven particle parameters don't update in viewport

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Hi all
I have a problem with Driven parameters in particle settings.
Here is an example:

  1. Add an Empty object
  2. Set key frame for Empty object ( location X = 0 in frame 0 and X = 2 in frame 100)
  3. Copy X location as new driver
  4. Add a plane
  5. Create a particle system for the Plane
  6. Set the particle to Hair
  7. Right click on Hair length slider and paste driver
  8. Play the animation

It should drive and update the particle hair length parameter but it’s not.

Now if you make dummy keyframe in any particle parameters (or changing any parameter with mouse) the driven parameter suddenly updates.
Is this a bug or missing feature !?

I’m using blender 2.90.1 on Win 10