WP 8 version disappeared from old phone after upgrading new phone to WP 10

I recently updated my Lumia 640 XL to WP 10 and updated some of the games to their Win 10 versions. After getting the "The Renaissance" achievement, I went back to my old phone (a Nokia Lumia 635) which is still running WP 8.1 so that I could load that version of the game so the achievement could pop there, too. However, the game no longer appears on that phone and when I attempt to install it again from the store, the game shows as installed and won't let me choose to install it again on that device. I removed it from the WP 10 phone but that didn't help. How can I reinstall the game on the WP 8.1 phone? Is it possible without completely resetting the phone; I don't want to do that and find that I've lost all progress in the games on that phone only to have Age of Empires: Castle Siege give me the same issue.

No matter how many versions you play, the achievements only appear once on your profile. They are not stackable.

Actually, they are stackable. Check TA ( http://www.trueachievements.com/Age-of-Empires/Series ) or my Xbox Live profile ( https://account.xbox.com/Profile?gam...yruleBalverine ). There's the Win 8; WP, Win 10, and iOS versions of the game, each with separate achievements. Either way, I reset the phone and was able to reinstall the WP version on the WP 8.1 device, popping the achievement.

You only have one castle seige on your xbox page that i can see. Each game here shows achievements but gamerscore doesnt increase on each platform. If you see more than one on your xbox page send over a screenshot as very intrigued to how its doing it for you

Here's a link to a screenshot from my phone that shows the Win 10 and two others.
https://1drv.ms/i/s!AqkkIMWDKxBRh7ZTil0XKUyXuiC3bg