Plugin Slider's Bullet Thumbnails / CSS Conflict

I've generated several sliders using a plugin called Wowslider which shows a slider with bullets at the bottom of all slides. And, when a bullet is moused-over, a thumbnail of that slide appears. The sliders work fine, but the bullet thumbnails do not. All thumbnails show the first slide only. The plugin vendor states:

Probably there is a conflict with some .css file. You can try to find in your .css file the lines like: td img { display: block; } or img { display: block; } And remove them.

As a check, I changed the theme to a WP default theme and all thumbnails show correctly. Any idea of what the conflict could be? Website is not live, but hosted on a local server. Can send screenshots if needed. Thank you.