Since this is an older post, I'm assuming you've solved this issue.
Incase others find this post, I'll post the link to the documentation
Hi Jeremy, welcome to the Adobe Analytics community!What if you created
a segment for 'All mobile users' and another segment for 'All desktop
users'? You could then look and compare the two fallout reports against
each other to see the comparison.
GTM tag (with document.write engine enabled) and it works fine.
Unfortunately, Google Tag Manager tags are limited to 10,240 characters.
My s_code.js script was due to advanced customization much larger. I
remember we resolved it by loading s_code library from external script
(js file placed on web server).I would suggest to use Adobe Tag Manager.