I have recently seen many people complaining about loosing obb files from Internal Storage even if they never formatted it while switching ROMs. This is troublesome for people with Games having large obb files to redownload over a limited-data plan or slow network.

Fix

If your /sdcard/Android/obb directory has no files which you had before switching ROM, check the following locations on your device with a root explorer like Mixplorer or alike-

1. /data/media/Android/obb
2. /data/media/0/Android/obb

If one of these locations have your game obb folders, move them to the other. This will make your obb files available on /sdcard/Android/obb

Worked? Buy something for yourself from my link of Flipkart. Thanks.
Curious why it worked?

Reason

You might be aware of the fact that /sdcard partition usually called “Internal Memory” is no more a physical or actual partition but an emulated one.

/data/media is the actual location which has /storage/emulated mounted over it. Depending on the ROM you either have /sdcard mounted over /storage/emulated for single-user or /storage/emulated/<UID> for multi-user ROMs. 0 (zero) is the User ID for the Owner of the device, hence /storage/emulated/0 is what /sdcard is mounted on for you in this case.

When you switch from a single-user ROM to a multi-user ROM or vice-versa, you get the problem of missing obb in /sdcard.

I have also noticed an uncommon situation. When you enable native Parallel Apps another directory with a new UID is created in /storage/emulated, like, /storage/emulated/999 which would be mounted as /sdcard for parallel apps. In this situation to avoid copying large obb files on both user directories, OS moves obb directory to /storage/emulated/obb and it is available as /sdcard/Android/obb for both users 0 and 999. Disabling Parallel apps could reverse this I believe, but do you really do that when you change ROMs?

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