Should split frames be able to solve this problem, or is there a general max resolution this still doesn't work with? I'm on a Geforce RTX 2080  8GB and I'ved tested on 4K and 1080p video using split frames, and still get OOMs

You still need to make the Session Size smaller, it seen that your GPU still don't have enough memory for 500 splits

From the screenshot you seem to have a similar problem as me. Almost 6 GB of memory is already allocated by other applications. Try closing all the programs (especially video/image editors such as Photoshop, Premiere etc.). Also try to connect your monitor to an integrated GPU if possible. That way, you'll have all the 2080's memory available for DAIN.

Doesn't make sense though, because 8GB-5.71GB = 2.29GB free space, but it is saying he only has 260.25 MBs free. 

We all seem to have this issue. Why is that?

Thanks.