Are you sure it's not being saved? I always seem to have exif data on mine.
What tool are you using to get the info?
I see the D7500 conforms to version 2.3.1 of exif, while my d7100 is 2.3.0. I have no clue what is different.
Also just looking at "exif exif info" between the two, I see different byte order? :
D7100:
MATH16-16 >> exiftool DSC_3678.JPG|grep -i exif
ExifTool Version Number : 12.00
Exif Byte Order : Big-endian (Motorola, MM)
Exif Version : 0230
Exif Image Width : 6016
Exif Image Height : 4000
D7500:
MATH16-16 >> exiftool DSC_6649.JPG | grep -i exif
ExifTool Version Number : 12.00
Exif Byte Order : Little-endian (Intel, II)
Exif Version : 0231
Exif Image Width : 5568
Exif Image Height : 3712