When creating a custom BPF with 12 or more steps, the last step is always not visible, even if you try to scroll all the way to the right. The last step only becomes partially visible (truncated) when it becomes the active step. Returning the active step to previous one make it not visible again. Issue was raised on Dynamics CRM 2015 and can also be reproduced on CRM 2016 Update 1 Online. Possibly related, but the section of the page does not scale full width either.
Tested with both IE 11 and Chrome.