That is the expected behavior, as our background animations are working that way that when the slide is changing, the current slide starts to fade out, and the next / previous slide immediately starts to fade in.
I can think about one workaround which is possible with the current settings. You could try to turn off the background animations and set the Animation to none: https://imgur.com/Mr61nmY
But I’m not sure if this is the result you are expecting.
One other workaround would be using image layers and layer animations (with disabled background animation) – just the layer animations are pro only features, so you can’t try that out.