Sign offs only showing first name

For the last couple of weeks, sign offs in KTD (for example, git so 1) only show my first name.

For example, my sign offs are showing as Signed-off-by: David <david@davidnind.com> instead of Signed-off-by: David Nind <david@davidnind.com>

The work around I've been using is to manually set $GIT_USER_NAME in kshell every time I run KTD.

Values in KTD's .env:

GIT_USER_NAME=David Nind

Value that shows when in kshell for echo $GIT_USER_NAME: David

Have tried putting name in quotes in .env, but it makes no difference.