Not sure if this is helpful but I am finding the same behaviour. A timecode of 18:12:16:07 in a 23.976 timeline comes back through vokouder as 18:13:21:20 when rendering a prores 422 HQ. Correct frames are coming through but it is changing the timecode.
In the logs under options it has the incorrect starting timecode listed. Using Voukoder 10.2 (10.2.149)