Tick 'Use Previews' bug on Export not fixed in V26.0.0.021 Beta

For info :

I have been spending a lot of energy following up with Adobe Support on two issues that have killed Smart Rendering in last versions of Premiere Pro (for nearly 2 years ?) :

1. Loss of Video Preview Files (random files)

2. Use Previews tick box not working in Media Export to speed up Exports (even if you have a green line above complex renders)

Status -

Support confirmed item 1 is still being investigated as of 11th June 2024. Not fixed.

On item 2 - Support asked that I tested the 'Use Previews' function as they were under the impression there was an early fix for this in Beta Version. (There is no mention yet in any documentation that I can see)

So I performed some tests on an existing project (ignoring Text Layers Issue) with latest Beta 26.6.0.021

Select Export Media with same codec as that used for Previews - in my case ProRes 422.

Export with ProRes 422

Select in and out points on timeline

Export starts - as soon as export reaches a clip with which has a preview with green bar (previously rendered) - GPU ramps up and export slows right down.  This happens a few times on similar encounters with Previews that should be available.  Premiere Pro is re-rendering whole timeline again !!

Conclusion - Use Previews Fix is not present in Beta version 26.6.0.021 as far as my initial testing shows

Have informed Adobe Support against a Case Ref as requested.