Intro page parallax issue

Hi,

There's something weird happening to the background image when I navigate away from an intro page and back again.  This is for on an intro page with parrallax (jarallax) e.g. the minimalist intro here https://mdbootstrap.com/angular/sections/intros/.

At first glance its not easy to spot as the default resolution hides the problem so please follow the steps below to reproduce the behaviour:

1. Open this link https://jarallaxissue.azurewebsites.net
2. Zoom out on the browser as far as you can, noting that the image takes up the whole screen.
3. click on "about" in the menu or the button in the middle. (observe the repeated image on the about page, Press F5 returns that page to a single image)
4. click home.  (observe the repeated image again)
5. press F5 to return the form to its original state. (single image) - update - just noticed that F5 is not working but reloading the original page shows the full image again.

I get the same behaviour if I navigate to any page from the home or about page and back again. Am I missing something obvious or is this a known issue?

My example site has no other styles other than the one from the example which I placed in the root styles.scss folder.  I don't get this issue if I remove the class="view jarallax" which of course is what I need to get the parallax effect.

Hopefully its an easy fix as this is driving me nuts.

Thanks,

Geraint