Commands behaving differently in script vs shell - powershell

Question

I've got two powershell functions in a file. The first one (Get-ImapAttachments) connects using the NetCmdlets IMAP cmdlets, downloads all *.csv attachments from any messages in the INBOX, and then moves the messages to another folder to keep the INBOX clean. I got this function from the NetCmdlets site, and tweaked it slightly for my needs. On it's own, it works the way I need it to.
I've written a second function (Import-D2LData) to process the CSV file. It's a badly formatted CSV file, complete with a report title on the first line, and the column headings are repeated every 23 lines or so. Since Import-Csv isn't quite as flexible as I need, I use a combination of get-content and select-object -skip 1 to start off the import, and basically build a long string to pass to ConvertFrom-Csv. If I run that function manually, it currently works the way I need it to, also.
The problem arises when I run it in the .ps1 file I've got them in. The first function fires off just fine, and the second one seems to. The ConvertFrom-Csv fails and I end up with a bunch of empty lines of output. The real strangeness is, I can use the . command to source the .ps1 file, and run the last 7 lines of the script (starting with the call to Get-ImapAttachments), and I get the expected results.
I'm sure I'm doing something pretty braindead, but after staring at the code for a couple of hours, I'm just not seeing it at this point...
# Needed for the IMAP Stuff
Add-PSSnapin -Name NetCmdlets -ErrorAction SilentlyContinue
function Get-ImapAttachments {
param(
[string] $server,
[string] $user,
[string] $password,
[string] $downloadDir="c:\temp\attachments",
[string] $folder = "INBOX"
)
$destFolder = "$folder.Processed"
$imapConnection = Connect-Imap -server $server -user $user -password $password
$m_messages = Get-Imap -connection $imapConnection -folder $folder
foreach($msg in $m_messages)
{
if($msg.ContentType.StartsWith("multipart")) #A MIME message with multiple parts
{
for($i=0;$i -lt $msg.PartCount;$i++)
{
if($msg.PartFileName[$i] -like "*.csv" ) #There is a CSV attachment
{
$localFile = $downloadDir + "\" + $msg.PartFileName[$i]
if( Test-Path -Path $localFile ) {
Remove-Item $localFile -Force
}
Get-Imap -connection $imapConnection -folder $folder -view $msg.Id -localfile $localFile -part $msg.PartId[$i]
Move-Imap -Connection $imapConnection -folder $folder -Message $msg.Id -Destination $destFolder
}
}
}
}
Disconnect-IMAP -Connection $imapConnection
}
function Import-D2LData {
param(
[string] $CsvFile
)
Write-Host -ForegroundColor Cyan $CsvFile
$file = get-content $CsvFile | Select-Object -Skip 1
$head = $file[0].Split(',')
$data = "$head`n"
foreach ( $line in $file ) {
if( $line -ne $file[0] ) {
$data += "$line`n"
}
}
$csv = $data | ConvertFrom-Csv -Header $head
$csv
}
Get-ImapAttachments -server imap.contoso.com -user sa_mailbox -password 'password'
$csvFiles = Get-ChildItem -Path "c:\temp\attachments" -Filter "*.csv"
foreach( $file in $csvFiles ) {
Import-D2LData -CsvFile $file.FullName
}

Answer 1

Well, it wasn't pretty, but I ended up breaking the functions into two different scripts. When that wasn't enough, I ran the first script in it's own PowerShell instance, which seemed to isolate the runspaces enough to allow both functions to operate properly:
$BasePath = 'Z:\scripts\Import-Data'
powershell.exe -NoProfile -command "& '$BasePath\fetch-attachments.ps1'"
& "$BasePath\process-attachments.ps1"
Not exactly an elegant solution, but it got me past the issues I was having...