Ogg/flac files are allowed to have the total sample count field set to unknown (aka 0). When this happens, File_Ogg (and by extension TMH) reports the flac file has a length of 0 seconds, which is wrong.
I think what needs to happen in these situations is to take the approx_granule_pos and divide by sample_rate.
To quote ogg/flac spec:
"Redundant fields in the STREAMINFO packet may be set to zero (indicating "unknown" in native FLAC), which also facilitates single-pass encoding. These fields are: the minimum and maximum frame sizes, the total samples count, and the MD5 signature. "Unknown" values for these fields will not prevent a compliant native FLAC or Ogg FLAC decoder from decoding the stream."