This happens when you try to pipe out from any of the Format-* commands.
The Format-List, Format-Table and Format-Wide cmdlets are special in PowerShell, in that they're meant to consume the pipeline, and transform it for display in the console. So, you can't pipe from FL, FT or FW into Export-csv. As Don Jones says "Format On the Right".
Don't believe me? Observe, as I run Get-Process, send it through Format-Table and then convert to Csv.
gps | ft | ConvertTo-Csv
#TYPE Microsoft.PowerShell.Commands.Internal.Format.FormatStartData
"ClassId2e4f51ef21dd47e99d3c952918aff9cd","pageHeaderEntry","pageFooterEntry","autosizeInfo","shapeInfo","groupingEntry"
"033ecb2bc07a4d43b5ef94ed5a35d280",,,,"Microsoft.PowerShell.Commands.Internal.Format.TableHeaderInfo",
"9e210fe47d09416682b841769c78b8a3",,,,,
"27c87ef9bbda4f709f6b4002fa4af63c",,,,,
"27c87ef9bbda4f709f6b4002fa4af63c",,,,,
"27c87ef9bbda4f709f6b4002fa4af63c",,,,,
It's even the same string! Why do we get this string? I really wish I knew, but I think it has something to do with the way the Format-* commands convert objects into text instructions for display in the console.
If you REALLY love the way your Format-Table looks, send it to Out-File, which is the only way to redirect the output of a Format-* command.
Another message is to use Tee-Object to dump a copy of your pipe to a variable, and then send that out to Export.
Get-Process | Tee-Object -Variable ExportMe | Format-Table
$exportMe | export-Csv .\Export.csv
I call this the 'have your cake and eat it too approach'.