Whatsapp: Export chat with media does not work properly

tl:dr; It's a WhatsApp limitation and there seems be to no workaround.

• Whatsapp export by mail has limitations. WhatsApp FAQ says

• If you choose to attach media, the most recent media sent will be added as attachments.

  
  



• When exporting with media, you can send up to 10,000 latest messages. Without media, you can send 40,000 messages. These constraints are due to maximum email sizes.

  
  

• This blog adds more details

A maximum of the last 10.000 messages are sent. However, if you have some videos or images, the number of exported messages might be much smaller.

WhatsApp will start creating a “package” with the latest Media files and text. It will put the last media files and messages first and then will stop when approximately 18 Mb of data have been packaged.

• If you have some videos in your chat, this could mean that you have two or three videos, some pictures and only one week of chat.

  
  



• If you have basically many pictures, you will be able to export about 50 to 75 pictures and a few months of chat.

  
  



• In case that you do not have many media files, you will be able to export a maximum of 10.000 messages with this system

  
  

• I couldn't find any such limitations for export to Google drive in whatsapp FAQ or on my search on the net but going by this issue on Google support and fair number of people who up voted this complaint, it seems to be common. As you can see, Google has washed their hands off and pointed to WhatsApp. You may like to raise this issue with WhatsApp
  and post your findings here to cover the Google Drive portion