NVD_BACKEND=direct doesn't work

[qaako]

Distro: Linux Mint Driver: nvidia-driver-575 Graphics Card: Nvidia GTX 960

When I use NVD_BACKEND=direct, vainfo fails to initialize.

NVD_LOG=1 NVD_BACKEND=direct vainfo                                                                                                                                                      
libva info: VA-API version 1.20.0
libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/nvidia_drv_video.so
libva info: Found init function __vaDriverInit_1_0
     98485.191973463 [46414-46414] ../src/vabackend.c:1872       __vaDriverInit_1_0 Initialising NVIDIA VA-API Driver: 0x63cdc3ff3f50 10
     98485.191978205 [46414-46414] ../src/vabackend.c:1894       __vaDriverInit_1_0 Now have 0 (0 max) instances
     98485.191979886 [46414-46414] ../src/vabackend.c:1919       __vaDriverInit_1_0 Selecting Direct backend
     98485.208674778 [46414-46414] ../src/direct/nv-driver.c: 190            init_nvdriver Initing nvdriver...
     98485.208687753 [46414-46414] ../src/direct/nv-driver.c: 195            init_nvdriver Got dev info: 100 fe 1 1
     98485.208708619 [46414-46414] ../src/direct/nv-driver.c:  36          nv_alloc_object nv_alloc_object failed: -1 0
     98485.208710153 [46414-46414] ../src/direct/nv-driver.c: 216            init_nvdriver nv_alloc_object NV01_ROOT_CLIENT failed
     98485.208712649 [46414-46414] ../src/direct/nv-driver.c: 278            init_nvdriver Got error initing
     98485.208717568 [46414-46414] ../src/direct/nv-driver.c:  79            nv_rm_control nv_rm_control failed: -1 0
libva error: /usr/lib/x86_64-linux-gnu/dri/nvidia_drv_video.so init failed
libva info: va_openDriver() returns 1
vaInitialize failed with error code 1 (operation failed),exit

I'm very new to Nvidia, this is my first discrete card and my first ever Nvidia graphics. I also can't really find the documentation on the NVD_BACKEND=direct variable.

[qaako]

Update: Here's a pastebin for the output of vainfo: https://0x0.st/K8-d.txt I realize the formatting wasn't good on my post and not sure how to fix it. Also, I tried switching to the nvidia-535 driver. This new pastebin is the output of vainfo using this driver. It's entirely possible I'm doing something wrong because I can't find the documentation for the NVD_BACKEND=direct env variable. Thanks for entertaining my issue and sticking this far.