We don't have a repro scenario, but it seems under specific circumstances an issue happens in the package manager, preventing the template window from retrieving information about the learning samples.

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*Actual results:* 
The template window is empty

*Expected results:* 
The template window contains all built-in VFX templates

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*Reproducible with versions:* 
6000.0

*Not reproducible with versions:* 

*Can't test with versions:* 

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*Tested on (OS):* 

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*Notes:*
*  This issue was raised by a customer on our discussion forum [here|https://discussions.unity.com/t/create-vfx-graph-menu-is-blank/1590519].