These solution options were taken after speaking with ESRI tech support. I use ArcMap 10.5 version.
Option 1:
Go to Customize tab and select Customize Mode


Under the Command tab, type in “export map” in the search menu. Under file, click and hold the “Export Map” command and drag it to the File tab on the main desktop interface. Drop it in the tab. Two Export Map options will have populated. Check to see if that fixed the issue.

If this doesn’t work go to Option 2.
Option 2:
This will require you to rename the Normal.mxt file embedded in the C:\ where ArcMap is stored. To locate the file path create a new document (Ctrl+N). See highlighted area in figure below. Write down or copy the file pathway somewhere, if you can’t remember the pathway.

** Close ArcMap before going any further.
Go to Windows Explorer and go to the Normal.mxt file. If your pathway was like mine, the AppData folder was hidden and I had to search “folder options” in the Control Panel. Select the View tab and select, “Show hidden files, folders and drives”. Click Apply. Continue back to the file pathway, AppData should be transparent, but available.

Rename the Normal.mxt to Normal_old.mxt

Restart ArcMap and the details dialog box should be available. FYI this change didn’t happen immediately. It took a couple minutes to take effect so may want to take a short break and return. If this solves the problem you can go back to the Normal.mxt file and delete the renamed file (there should be a new Normal.mxt).
After this had been corrected, I discovered another issue with the Export map dialog box. I use a double screen when using ArcMap. I use the second screen because it’s much bigger than the laptop screen. It’s also a TV and not a computer monitor and it’s connected with an HDMI cable.
The issue is if I try to export a map with the second screen, I get the same problem as described here. However, if I drag ArcMap to the laptop screen, the export map dialog box returns as it should.