Doc Type customization is not detected for exporting into custom app

I’ve added following three fields in Journal Entry Doc Type and wanted to export the customization to my custom app but I am not able to export as the changes are not detected. However, few days ago I’ve added a custom field named From Purchase Invoice to the same Doc Type and that time I was able to export that custom field to my custom app.
But this suddenly it stopped working after I customize the Doc Type for the second time. What could be the reason? How can I solve this?

SS attached: