Previously customized DispForm.aspx and now PowerApps custom form doesn't load in view mode

[Bynum Hoekstra]

Before I describe my issue, first I want to confess to not following best practices when I was less-experienced. In order to create a solution that displayed "related" documents (via a lookup column) to a SharePoint list item, I customized DispForm.aspx in SharePoint Designer. I even went as far as to create a copy of DispForm.aspx (called DispForm2.aspx) before I made my SPD customizations. 

Fast-forward 4+ years and now the same list needs a custom PowerApps form because PowerApps is a bit more modern looking than the old custom list form. So far, everything is working fine with the PowerApps custom form for this list, except that when you click the "Copy link" next to an item in the list, it still goes to the old DispForm2.aspx page. 

I've tested, and ViewForm.aspx and EditForm.aspx correctly go to the new PowerApps custom form, but just DispForm2.aspx goes to the wrong (old) customized form. Does anyone know if there's a way to get out of this problem without just copying the list data and recreating it from scratch? 

[#2]

Switch the list experience over to modern?

[#3]

@Chris Webb Unfortunately, the list is in Modern mode and still shows this old DispForm2.aspx page. 

[#4]

Remove all the customization done in DispForm.aspx, such as Media webparts, external js. Only keep the default webpart which shows all the columns without any JS and Save the page. Next time when you will load the page, it will show the PowerApps form. Spent lot of hours myself to figuring this out. See if it works for you.

[#5]

Did you ever get this issue resolved?
JM

[#6]

In the end, we copied the content from the list into a new site and started clean.