Hmmmm… well, looking at the image EXiF information I found out this image: https://i2.wp.com/www.ohiogirltravels.com/wp-content/uploads/2016/05/20160319_160358-e1463067570368.jpg?resize=550%2C978 has:
EXIF IFD0
Image Width 5312 pixels
Image Length 2988 pixels
Camera Make samsung
Camera Model SM-G920V
Picture Orientation rotated 90° (6)
X-Resolution 72/1 ===> 72
Y-Resolution 72/1 ===> 72
X/Y-Resolution Unit inch (2)
Software / Firmware Version G920VVRU4BOK7
Last Modified Date/Time 2016:03:19 16:03:58
Y/Cb/Cr Positioning (Subsampling) centered / center of pixel array (1)
Notice: Picture Orientation rotated 90° (6)
Another image: https://i2.wp.com/www.ohiogirltravels.com/wp-content/uploads/2016/05/IMG_4345.jpg?resize=550%2C825 has:
EXIF IFD0
? (0x000b) Windows Photo Editor 10.0.10011.16384
Camera Make Canon
Camera Model Canon EOS REBEL SL1
Picture Orientation normal (1)
X-Resolution 72/1 ===> 72
Y-Resolution 72/1 ===> 72
X/Y-Resolution Unit inch (2)
Software / Firmware Version Windows Photo Editor 10.0.10011.16384
Last Modified Date/Time 2016:05:12 12:28:26
Artist
Y/Cb/Cr Positioning (Subsampling) co-sited / datum point (2)
Copyright Owner
Microsoft.Padding 0x1cê0x08
Notice: Picture Orientation normal (1)
Now, in my case with Firefox, both of these images are in vertical rotation and look correct. Perhaps Chrome/MAC is looking at the Rotation setting and rotating them. Just guessing.