I just recorded a game with OBS, using HEVC encoder with mp4 container.. If I open the file with VLC or PotPlayer or avidemux I get all of my 3 audio tracks, while if I open the file in DR all I get is a video track with "embedded" audio, no separated audio tracks.
Today I bought the "HEVC Video Extension" App from Microsoft Store to have HEVC working with DR, but I have this issue now.
I just checked and found out that for H.264, CBR is observed quite well. I have my stream set to 25Mbit/s and it goes up and down by a couple Mbits, depending on what I'm doing while playing games.
On the other hand, H.265 is totally VBR, going from as low as 900Kbit/s up to the value I've set (same 25Mbit/s as H.264).
I have to say though, that I haven't had any particular issue editing and delivering HEVC footage so far.