Lightroom 1.3.1 doesn't treat negative altitude correctly

[ATJ-renamed]

I'm using GPS data for my diving photographs. I am able to determine the depth a photograph was taken because my dive watch records my depth every 5 seconds. I create a GPX file with the depth recorded as a negative altitude (which is appropriate) and synchronise it with my photographs. When I import the photographs into Lightroom (or read the metadata from file), Lightroom shows the altitude as positive.

The GPX file shows the data correctly.

<wpt lat="-34.'7'55556'" lon="151.15722222'">
  <ele>-6.4'''''</ele>
<time>2''8-'7-26T'2:29:'2Z</time>
  <name>WPT776</name>
  <cmt>WPT776</cmt>
  <desc>WPT776</desc>
</wpt>

Opanda IExif 2.3 also shows the data correctly

[GPS]
GPS Version ID = Version 2.2
GPS Latitude Ref = South latitude
GPS Latitude = 34°4'14"
GPS Longitude Ref = East longitude
GPS Longitude = 151°9'26"
GPS Altitude Ref = Sea level reference (negative value)
GPS Altitude = 6.4m
GPS Time Stamp = '2:29:'3 UTC
GPS Satellites = '
GPS Map Datum = WGS-84
GPS Date Stamp = 2''8-'7-26 UTC

But Lightroom shows it as this:

 

[Sean McCormack]

I remember seeing this come up before.. It's a bug.