Hi @Anonymous,
If you customized the form using the SharePoint integration object, in addition to the usual OnStart and OnVisible actions that happen when you open the app, the SharePoint integration object has triggers for OnEdit, OnNew, OnSave, etc.
The OnEdit action should be set to EditForm(Name_of_form) to put it in edit mode.

The form has an Item property that shows the selected record by default. When the form is in edit mode, it will populate that selected record and each of its fields. When the form is in new mode, it will ignore that record and keep everything blank.

Can you check that the form has an Item property and EditForm is executed?