Do you have Edxposed? You need to black list all Dolby components (both DDP and the stock Dolby Atmos). Here are the installation steps that I did to install DDP, V4A, Ainur Sauron and Audio Compatibility Patch on my OP7Pro running OOS 10.3.1:It's so weird in my OP7P. Before flashing DDP 7.2, I have Viper4a and it works great. After flashing DDP 7.2, DDP stuck at opening screen and cannot enter its main screen. If I switch viper4a off in magisk and rebooting phone, DDP works.
It means I just can choose one of both between DDP and viper4a.
How to make both work together ? (My another phone - Pixel4xl can make DDP AND Viper4a work together !)
1. Remove all audio mods from Magisk Manager and reboot.
2. Install DDP, Busybox, Ainur Sauron (optional) and ACP (optional) but DON'T REBOOT YET. Just have them installed in Magisk Manager. They should say they will be updated in next reboot.
3. Go to V4A app (I'm assuming you're using V4A 2.7.1.0) and install drivers. This will reboot your phone.
4. Blacklist all Dolby related things in Edxposed Manager if you use it and flash Audio Modification Library in Magisk and reboot.
5. If the audio mods work, congrats ya did it! If not, remove ALL Magisk Modules except Busybox and try again.