This might be not a bug but intentional limitation. So, I installed Voukoder 7rc1 (7.0.113) today and was in the process of selecting some VBR settings for nvenc export that were previously loaded from a preset. My buffsize was previously set to 500000 kbit (500Mbit), and it seems the newer version didn't load it so it seems to have reverted to default 15000. When trying to change it, I was getting an error window saying
And soon later Premiere crashed. I didn't notice anything in particular in voukoder log. The version I was using before when I made the preset with 500000 kbit -buffsize preset was Voukoder 6 (6.0.85). So I went back to last stable v6.2 release, now I notice it won't allow me to input a value above 288000?
Now, I've only recently started using that value since I've read somewhere it should be 2x of max bitrate. I don't know if it's ok to set it that high but I haven't had problems with it in ffmpeg + nvenc.
My current driver is 257.30 and I've verified that I can export h264_nvenc with Voukoder 6.2 just to eliminate possible issue on my end.
It's possible I'm just misunderstanding something, or there's some ffmpeg/nvenc limitations or dependencies on other settings. But I didn't fun into this on 6.0.85
edit: I'm sorry, it probably was always this way. So when saving the preset in V6.0 it didn't get saved as -buffsize 500000 but got reset to 15000. I can't verify inside .epr file itself but probably so.