.jpg vs.e.jpg and datestamps on photos

I use an Apple 12Pro downloading photos to my pc using File Explorer.

We noticed that many photos aren't showing the datestamp anymore. The app (ProCamera) is defintely set to record that information.

I dug around a little and noticed that the *_E.jpg files do show the date stamp whilst the standard *.jpg files don't. However not all jpg's have _E.jpg versions.

On further investigation - not all photos have an *_E.jpg version on the phone - and only the E version contains/show the datestamp.

Somewhere I read that the E version is created by apple when the photo is edited - but I did not edit any of them at all - not on my phone nor on my pc. 

Can someone explain the issue and ho wto rectify that? We defintely want the date/timestamp showing on our photos.