bought lumia 640xl and lumia 730, repenting now. whatsapp is not detecting its own folder. not only that, infact whatsapp folder is not able to see in photos gallery as well. i am confused now whether whatsapp problem or windows problem.
- Goto the Location of the Whatsapp folder which is not been detected by your photos app and Whatsapp
- Rename the folder to Whatsapp1 or whatspp2 or anything u like
- Move to whatsapp and download some pic or video which was sent in whatsapp
- now mobile has created a new folder "whatsapp". This will be detected by the photos app and whatsapp too You can then move the contents from whatsapp1 folder to your new whatsapp folder
This worked for me