I may not be much help-- I've never used the Apple Devices app. I use a Mac and iCloud to synchronize pictures, and that's seamless. And we can't use cable syncing if we use iCloud, so my experience is limited. If you haven't yet, check this out:
Sync your Windows device and iPhone, iPad, or iPod - Apple Support
It's from the User's guide to the Apple Devices app. It might tell you what you need to know, and someone with real Windows experience may come along later.
Hmm--one way is to take the computer out of the loop. Save the pictures to an external drive. Then you can plug the drive into the iPad, and it will show up in the Files app. Then you can select them, choose Share>Save Images, and they'll go to the iPads Photos Library.