It’s probably related to the fact OBS is 64-bit and the filter 32-bit.
A 32-bit app cannot see 64-bit drivers so I suppose this is also valid the other way round.
As Henrik mentionned, we created the filter mainly so that we can use the same decoding engine in webcamXP that we developped initially for Netcam Studio. That’s why we created only a 32-bit version.
Technically, we could potentially prepare a 64-bit version of our filter however it has never been planned / in the pipe on our end as we had no real need for it…