DTS:X not in drop down options with app installed

In my games and apps, pressed the start button on your controller when Destiny is highlighted. This will bring up a drop down menu with some options. Select manage game, and you will able to scroll down to ready to install. This will show any dlc that your
account owns for the game. You should be able to install the dlc from there.

It has been a while since I have played it but you are correct it would be under the options like the rest of the air drops it would show a choice for the independence drops.

One way to check to see if it is installed is to go into my games and apps and highlight the game hit the menu button on controller and go down to manage game and that will show you any DLCs currently installed and if not installed will show you what ones
are available to install.

I found the problem I believe, is your Xbox in the Insider program and in the leap ahead group ?

I just dropped my X back down to the Alpha group and indeed pressing and holding the left thumbstick and X does show your hidden games/apps so I can only assume it's a problem with the leap ahead update. For the leap ahead that just doesn't work but my previous
suggestion does. So either drop down to the Alpha group or use the other option.

Change Xbox app storage settings

Click on the profile icon near the top-right and select Settings from the flyout menu. Go to the General tab. Click on the drop-down menu under Change where this app installs by default. Select the desired drive from the list of options.

when you click install it should give you an option for which drive you want to install it on.

Click on the drop down and select your prefered drive.

if it doesnt give you an option, open the start menu and type in "apps & features" open it then find the games you want to move click on it and select move. Now you can move your games to a different drive