Weight before session field empty

[k1o0]

I notice there's a new field in sessions called 'Weight before session'. It doesn't seem to be populated for our mice, even though there are weights recorded before the session. The documentation for the sessions end point doesn't mention any field so I assume this is a computed field. Here's an example sessions and weight record:

https://alyx.cortexlab.net/admin/actions/session/10e35ca0-a49f-4f23-836f-6e302e2b87ad/change/
https://alyx.cortexlab.net/admin/actions/weighing/f05aebb0-fff1-436d-93e8-454ff563c454/change/