Environment

Microsoft Windows [Version 10.0.18363.836]
Windows Terminal version: 1.0.1401.0

Steps to reproduce

1. Set up a profile to have a background image
2. Close all terminals
3. Open the terminal via wt split-pane, or wt -p "Command Prompt" ; split-pane -p "Windows PowerShell"

Expected behavior

Terminal to open with both background images shown

Actual behavior

Only a single pane shows the background image.

wt split-pane;split-pane also works correctly, and shows the expected behavior.