[Plugin: Testimonials Widget] Character limit not working?

I have some long testimonials and would only like to show only part of them in a block on my page with a “…” or “read more” link. I thought that setting the character limit would ‘chop’ the text off – but it only seems to exclude any testimonials over that limit from being displayed at all (is this the cause of people getting only the title & no testimonials as in some other posts?).
Also 0 the ‘limit’ in the shortcode seems to refer to the number of testimonials displayed – not to the character limit? Is there a parameter to the shortcode to limit the number of lines/character displayed?
Sorry a bit new to this – am I missing something obvious??

https://www.ads-software.com/extend/plugins/testimonials-widget/