This theme isn’t supported anymore – and all the fixes I found to create a page that will display all collections was futile. There was a great bit of code on github with a solution that worked for many, but it didn’t include a stylesheet and the Mosaic theme did not support it by default.
Rather than create a Shylsheet for the feature from scratch, and believe me I started to, I kept searching.
I found a post from 2015 which surprisingly solved my problem and will hopefully help you as well. It was actually super simple and I’m annoyed I didn’t notice before. I imagined the theme was just broken, as you may be as well.
So, there is already support for “All Collections” to show on a page in the Mosaic theme. You may have noticed it in the breadcrumbs like me or in a menu. It can be found by going to the code editor of your theme ( under “Online Store” then the “actions” drop down above your theme choose “edit code”) and looking under “Templates” for “list.collections.liquid” – open this and find the line :
{% for link in linklists.all-collections.links %}
Now, you can either go to your “Navigation” section under ” Online Store” and create a collection called “Collections” or you can create one like the one they suggest called “All Collections”.
IF you want to change it to “Collections you need to change the line of code above to:
{% for link in linklists.collections.links %} This is what messed me up in the first place. Their page to display Collections is called mysite.com/collections – but the link list they want the Handle to be called “all-collections” – in my poking around to try and sort this out it would have incidentally worked if they had just been consistent with the use of the word “Collections” rather than throwing an “all collections” in there.
Hope this helps someone!
*Maybe this was in the theme documentation somewhere but I was unable to find it or any support for the theme online anymore.