Use the following HTML markup to reproduce the issue:

<div 
    tabindex="0"
    role="slider"
    aria-valuemin="0"
    aria-valuemax="100"
    aria-valuenow="10"
    aria-orientation="vertical"></div>

NVDA reads this markup in the following manner:

slider 10

The expected pronounced state is the following:

vertical slider 10

This issue is reproducible in the Firefox and IE browsers.