[totalslider] shortcode doesn't recognize group's slug properly

I’m using the [totalslider] shortcode to place a slider on a page:

[totalslider group=”verbolten”]

I have a slide group called Verbolten, slug: verbolten (no capital). It has 4 slides in it. However, the page currently gives an error:

Total Slider: Could not find the selected slide group to show. Does it still exist?

Yes, it still exists. ?? How can I make the slides show up?

Note: The site is using a WooThemes premium theme, but per WooThemes’ current policy they do not answer support queries related to theme customization.

https://www.ads-software.com/plugins/total-slider/