The folder path in a pop-up does not open with Windows Explorer even when 'file:///' is added to the folder path. When the Image option does not exist, the folder opens in ArcGIS Pro's dialogue. However, when the Image option exists, the folder opens in Windows Explorer.
This issue is not reproducible. If 'file:///{URL_field}' is written directly in a text element, it is interpreted as a text string. It must be configured as a hyperlink in order to open in Windows Explorer as defined.