We would recommend to update Digital Photo Professional in case you are using the version that was available when you've purchased the EOS 1200D. Canon will update the software to support the image format when newer Canon cameras are released. We do show that there has been a couple of years between the release of the EOS 1200D and the EOS 80D camera bodies.
You may click on the following link to download the latest version of Digital Photo Professional 4:
The website will ask for the serial number shown on the bottom of the camera body and you may use the serial number from either camera to download the software.
After installing the latest version, you should be able to open, edit and manage the picture files from the EOS 80D camera.