I have an approval workflow and I created a custom Nintex mobile task form for SharePoint 2013 on-premise.  When users get an approval Email, they can click on the approval task and it will display the Nintex form.  However, when the user clicks on the approval task link in their Email, it redirects to the SharePoint OOTB task form instead of the Nintex mobile task form.

Ex:

On their mobile device, the user is directed here:

https://server/sites/Home/_layouts/15/mobile/editforma.aspx?List=de4ad857%2D878e%2D403a%2Da630%2Dc903d90fe0b0&ID=254

They should be directed here:

https://server/Home/_layouts/15/NintexForms/Mobile/DispForm.aspx?List=de4ad857%2D878e%2D403a%2Da630%2Dc903d90fe0b0&View=5a1debf6%2D565b%2D460b%2D8836%2Dfc9bc41280a4&ID=254

Can anyone advise how to fix this so the user is directed to the Nintex mobile task form?