Your code looks fine to me, I can only speculate for reasons.

Could you try it with the -NoHeader option? This is available only after Powershell version 7.4 so pls make sure you have the version requirement.

if (-Not (Test-Path $CSVFile)) {
    $logEntries | Export-Csv -Path $CSVFile -NoTypeInformation
} else {
    # Append with the -NoHeader option
    $logEntries | Export-Csv -Path $CSVFile -NoTypeInformation -Append -NoHeader
}