When the roPosterScreen specifies a List Style of "flat-episodic", with both SD and HD posters defined and no episode number defined for the content, the side posters are not displayed in Version 7.0 build 9044. They do display correctly on the Version 3.1 firmware, however. I just noticed this (in my What's On Channel, and also on the Nowhere TV Channel), so I'm not sure how recently this bug was introduced.
Here's some code to reproduce the issue:
Sub Main ()
port = CreateObject ("roMessagePort")
ui = CreateObject ("roPosterScreen")
ui.SetMessagePort (port)
ui.SetListStyle ("flat-episodic")
contentList = []
For i = 0 To 6
contentList.Push ({ ShortDescriptionLine1: "Hello"
ShortDescriptionLine2: "World"
SDPosterUrl: "pkg:/images/PosterSD.jpg"
HDPosterUrl: "pkg:/images/PosterHD.jpg"
})
End For
ui.SetContentList (contentList)
ui.Show ()
While True
Wait (0, port)
End While
End Sub