Can't get images to disappear and new images to appear based on timer

Hi Lectora community,

I'm really hoping someone can help me with this:

Situation: I've recorded some audio for a page in my training. Throughout the audio, I want different pictures to come up and then disappear and others to come up after it. (Imagine the audio "Once upon a time there was a girl [pop up picture of a girl] and a magic unicorn [picture of a unicorn]. They lived out on a magic farm in la-la land [hide pictures of girl and unicorn, pop up picture of cute magical farm]"

So, it seems I can create actions that are prompted by the timer such as to make the new images pop up on the screen, but the same is not working when I want them to disappear. What happens is they flicker and disappear for a second, but then they return.

So for instance

action > on timer (8 seconds) -- show "unicorn"

action > on timer (15 seconds) -- hide "unicorn"

When 15 seconds rolls around it usually flickers gone for a second and then returns ... and sometimes occasionally flickers again (though not ever 15 seconds as far as I can tell)

I've tried doing this a few ways

1) the individual action items for each image I want to pop up and disappear [as a side note, I find it ridiculously annoying that I can't have one action with multiple responses without grouping things]

2) I've tried setting a timer so that at 14 seconds a variable is changed (variable "turnoff") and then at 15 seconds I say "on timer -- 15 seconds -- hide "unicon" if turnoff is set to yes)

Can someone help me? This is really important for a project I'm working on and I just can't believe I can't figure out why I can't make things permanently disappear!

Thanks so much!

-Heather

PS: I have Lectora Enterprise edition