'Back To Parent' not showing on Reporting Server 2016 after migrating from 2008

I've recently migrated a report from 2008 to 2016 Reporting Services and for some reason the 'back to parent' button which takes me up and down drilldowns as has stopped showing.

This is what it should look like:

I've read around that people have manually added a 'back to parent' button through using history.back but this will not work for me. The report is not a 'classic' SSRS report in that there is a .rdl file that I can edit. What happens is that the report is driven off of a series of tables (such as lines, headers and some figures) that populate a design table that we can see.

I was wondering if anyone has experience anything like this before when migrating across, or perhaps a DBA might know of a flag that needs setting up on the server that may have been missed?

After a long time searching around online, I've finally found the answer.

I needed to add the following line to the end of the report link:

&rc:showbackbutton=true