Please note that Juicebox v1.5.1 has not yet been integrated into Showkase but, until the next version of Showkase is released, you can download Juicebox-Pro v1.5.1 separately and integrate it into your Showkase site by following the Installing a Pro Viewer instructions.

No problem at all.
I appreciate you posting the link, though. I would never have found the source of the problem without seeing your gallery's configuration options. Thank you.

Thank you very much for the quick help

Holger

PS.: If it's okay, I remove the link to my home page again.

Your gallery sets showSplashPage="NEVER" so, on a mobile device, Small Screen Mode is used without a Splash Page.

I have now been able to replicate the problem in a test gallery of my own.
The problem is with Juicebox rather than Showkase.
It is caused by a combination of the following two configuration options in Small Screen Mode:

autoPlayOnLoad="TRUE"
showSmallThumbsOnLoad="FALSE"

I have logged a bug report with the developers and the problem should hopefully be resolved in the next version of Juicebox.

In the meantime, as you do not use the Splash Page or any regular Small Screen Mode functionality, you might be able to work around the problem by setting:

screenMode="LARGE"

... in the Juicebox Gallery Page's 'General (Pro)' section.

Thank you for the fast answer!

Meanwhile, the gallery is built on, but with a time lag of about 10 seconds.

Here is the link to one of the galleries:

.de/1/galerie-03

but pinch I can so well live with it.

Here are the answers to your questions:

1) iOS: 9.3.2

2.) Safari

3.) Theme Kosel

4. The issue of "Splash Page" I did not understand.

The problem occurs under both 4G and below WIFI.

Thanks for your help
Holger

Please also let me know the following.
What version of iOS do you use?
What browser(s) do you see the problem in (Mobile Chrome, Mobile Firefox, Mobile Safari)?
What Showkase theme do you use (Boma, Kosel, Maribo)?
Are you referring to the Splash Page on the Juicebox Gallery Page or the expanded gallery (after clicking the Splash Page)?
Thank you.

I have been unable to replicate the problem myself so hopefully with some additional information and being able to see your own gallery for myself, I should hopefully be able to help further.

In the meantime, if you are currently viewing your Juicebox gallery over a 3G or 4G connection, please try using a wfi connection instead. This may or may not be relevant but it cannot do any harm. Perhaps this Juicebox FAQ will help:
Why can't I view my gallery on a 3G mobile connection?

If on an iPhone 6 gallery visits, as long as the phone in portrait orientation is, no image appears. Only when I turn the phone to landscape the gallery appears completely normal. If I then back to portrait mode change the gallery remains visible.

What can I do?

Sorry for the Bad English. It is google translate.

Thank you very much
Holger