You can use a workaround i this case. Open up wp-content\themes\replete\includes\helper-slideshow.php and replace:
if($this->slideshow_poster == 'poster')
{
if(avia_is_overview())
{
if(is_array($this->slides)) { $this->slides = array_slice($this->slides, 0, 1); $this->type = $this->defaultSlider; }
}
else
{
if(is_array($this->slides) && isset($this->slides[1])) $this->slides = array_slice($this->slides, 1, count($this->slides));
}
}
with
if($this->slideshow_poster == 'poster')
{
if(avia_is_overview())
{
if(is_array($this->slides)) { $this->slides = array_slice($this->slides, 0, 1); $this->type = $this->defaultSlider; }
}
else
{
if(count($this->slides) > 1)
{
if(is_array($this->slides) && isset($this->slides[1])) $this->slides = array_slice($this->slides, 1, count($this->slides));
}
else
{
$this->slides = array();
}
}
}
Then go to Theme Options > Layout & Settings and search for the "Slideshow behavior on overview pages" dropdown. Select the last option ("Display only single image on overview pages and all slideshow images except the first one on single entries"). By going this way you won't see a slideshow if you just add one image to an entry.