Issues on iOS with Safari?

I am not aware of any problem.

For example, this page works fine for me on my iPhone.

Please post the URL of a page that has a problem

Take a look at spacracing.com

The very first “square” is actually this plugin. Works fine on desktop, but not working on iOS 9 for any of us on Safari.

This is a screen width issue rather than a device issue. You can reproduce it on a PC/MAC simply by making the window smaller.

I tracked it down to a media query in your WordPress theme.

The Slickr Flickr slideshow is behaving correctly; it is the theme that is the issue.

It sets the container element’s height to zero and 50% padding at the top pushes the slideshow behind other elements, leaving the blue square.

@media screen and (max-width: 885px)
.blog .site-content .hentry, .archive .site-content .hentry, .search .site-content .hentry {
    width: 50%;
    height: 0;
    padding-top: 50%;
}

If you remove the height and padding restrictions the slideshow is visible and plays correctly.

(However I do not why your theme would wants to set the height to zero so you need to check for yourself if this change has any undesired side-effects)

The problem is at line 1583 of https://www.spacracing.com/wp-content/themes/pictorico/style.css?ver=4.2.2

There is a second media query at line 1603 in the file that causes the same issue:

@media screen and (max-width: 590px)
.blog .site-content .hentry, .archive .site-content .hentry, .search .site-content .hentry {
    width: 100%;
    height: 0;
    padding-top: 100%;
}

Adding something like to your theme might be solution:

.site-content .home-page-sidebar .hentry{
    height: auto;
    padding-top: 0;
    width: 100%;
}

But inside a media query

@media screen and (max-width: 885px) {
  .site-content .home-page-sidebar .hentry{
    height: auto;
    padding-top: 0;
    width: 100%;
  }
}

Great, that did it. Thanks so much for looking into it!

Glad it is working.

A great plugin review would really be appreciated. Thanks