Playback returns to previous time in seconds after seeking.
I found that the raw_set function in the VorbisFileInstance.cs doesn't set the lastStreamPosition property,
There is a patch below and the whole file as an attachment.
312a313
> lastStreamPosition = vorbisFile.datasource.Position;
331a333
> lastStreamPosition = vorbisFile.datasource.Position;
456a459
> lastStreamPosition = vorbisFile.datasource.Position;
Patched source file