Gallery Layout

Hi
am hoping you could help.
Having trouble with code for gallery.

The requirement is for a two column masonry gallery, 1 pixel gap, each image linking to lightbox and with theme animation.
The code (below):
a) was created in the Default Editor box ( not advanced avia layout) using shortcode insert and then pasted into a Formidable Pro Form- Create Custom Post section with [341…] being the Form Field for multi-uploaded images (gallery images).
b) creates one row and two columns, but only displays one image (in the second column). The other uploaded images are not displayed?

[av_masonry_gallery ids='[341 show=id]’ link=”file” items=’12’ columns=’2′ paginate=’load_more’ size=’flex’ gap=’1px’ overlay_fx=” caption_elements=’none’ caption_display=’always’ container_links=’active’ id=”]

I have tried may variations including code example below – which displays two columns but tiny thumbs and overlapping layout:

[gallery ids='[341 show=id]’ style=’portfolio’ preview_size=’portfolio’ crop_big_preview_thumbnail=’big-crop-thumb’ thumb_size=’portfolio’ columns=’2′ imagelink=’lightbox’ lazyload=’deactivate_avia_lazyload’ show=id link=”file”]

It was made using the insert gallery shortcode (as opposed to avia masonry gallery as per top code)

Thanks in advance.
Best
Chris