Here's what I have:
Add-PSSnapin sqlservercmdletsnapin100
Add-PSSnapin sqlserverprovidersnapin100
Invoke-Sqlcmd -inputfile "somefile0.sql" -Server "server0" -Username user0 -Password password0
Invoke-Sqlcmd -inputfile "somefile1.sql" -Server "server1" -Username user1 -Password password1
Each Invoke-Sqlcmd run by itself runs fine. When placed in a script that reads like above, the last Invoke-Sqlcmd returns no results to the screen.