Issue update field SharePoint Powershell & CSOM

Question

Hello,

I using CSOM and PowerShell. and I have a libraby who uses a specifique content type.

When I try to update fields from a document who uses this content type, I have some issue on a few fields or it doesn't work.

for exemple when im doing

$myLibrary.Fields a lot of information about each field is return, no one is missing.

When I do $myLibrary.Fields.GetByInternalNameOrTitle('StaticNameWhoWork') that showing me up the informations about the field.

But when im doing this one a none working one $myLibrary.Fields.GetByInternalNameOrTitle('StaticNameWhoDontWork') the information disappears exemple :

TypeDisplayName      :
TypeShortDescription :
InternalName         :
Id                   :
EnforceUniqueValues  :
Title                :
Description          :
Group                :
DefaultValue         :
ValidationFormula    :
ValidationMessage    :
FieldTypeKind        :
TypeAsString         :
FromBaseType         :
Sealed               :
CanBeDeleted         :
Required             :
ReadOnlyField        :
Hidden               :
Direction            :
Sortable             :
Filterable           :
SchemaXml            :
StaticName           :
Scope                :
Context              : Microsoft.SharePoint.Client.ClientContext
Tag                  :
Path                 : Microsoft.SharePoint.Client.ObjectPathMethod
ObjectVersion        :
ServerObjectIsNull   :

So i can't update this one :(

Thanks,