I have made the following work-around and this is working:

jb2.onInitComplete = function() {jb2.showImage(1);}

The problem does not exist in mobile browsers of any kind, Windows 10 mobile, Android or Apple. My gallery is always in Large mode.

Feature request
Please create an API to reload or refresh any Juicebox gallery. I was thinking like:
jb.refresh
or
jb.reload

Looks good but actually I was more thinking of something like:

jb.refresh 
or 
jb.reload

Hi Steven,
I have add the setGallerySize( width: int, height: int ). I get an error message:

Uncaughty type error: Cannot read property 'position'of null
at set_containers_size_and_position (eval at <anonymous> (juicebox.js:14), <anonymous>:1:290533)
at repaint (eval at <anonymous> (juicebox.js:14), <anonymous>:1:226204)
At object.glryRepaint (eval at <anonymous> juicebox.js:14>, <anonymopus>:1:226204)
at Object.setGallerySize (eval at <anonymous> (juicebox.js:14), <anonymous>:1:293212)
at index_test.htm:333
at dispatch (jquery.min.js:3)
at q.handle (jquery.min.js:3)

It is working but ruined the resize of my liquidslider app until I do an F5 in my browser. Please check if I have done something wrong. What I find odd is that my Galleryheight is correct but the Gallerywidth is at 100%
Please take a look and let me know.
I have update the test page : https://www.delosgaia.nl/index_test.htm

Hi Steven,
I have made a testpage, see https://www.delosgaia.nl/index_test.htm

Just open this page in any browser in a width larger then 910 px, check the section under div class="sidebox"><div id="header">
You will find the id="box_slideshow"

Then resize the browser below a width of 910 px and check this section again.

Compare the height of <div id= "jb-glry-id-1"......> with the height of <div class="liquid-slider"......>. They are equal.

Hi Steven,

Thanks for your answer, I have to correct something. This is not correct:
If a galleryWidth or galleryHeight ends with a percentage character ('%'), then the dimension will be a percentage (of the gallery's parent container). This is not correct, it is the page height Juicebox is using as Galleryheight.

I have set the parent container in VW width:100VW, height:29VW (this is legitimate)  and galleryWidth and galleryHeight both in 100%. The first div below the DIV with galleryWidth and galleryHeight does have width:900px (is correct, devicewidth = 900px) but height is set as 8723px. This is the total height of the page and is 5 DIV higher in rank

To be sure, I changed height of parent DIV in 29VH but still 8723px.

So my conclusion is that when Galleryheight is in percentage Juicebox is not using the parent container for calculating the height of jb-glry-id-0 but the page height and in my case this is 900px by 8723px. (element.style=height: 10163px;)

It could be that this is a feature but it isn't because you are writing about the parentcontainer, so it must be a bug in the calculation. Only when you set the galleryheight in PX the publishing of the gallery is correct, in my case
No problem, I can use Javascript for calculating the correct Galleryheight in PX. You have made once a nice script for this except it don't work for me. Juicebox is still looking for an higher DIV with an element.style=height:10163px

Control of Caption Position in Small Screen mode. Picture has never the size of the mobile screen.

Classes definitions for caption are changed in JB 1.5. I had a similar problem.