When using eZ Content Staging 4.7.1, if we set TransportClass=eZRestApiEmbeddedClientStagingTransport471 we won't be able to sync eZ Flow block items.

Setting the environment:

Install two eZ Publish 4.7 instances in order to make them accessible in independent hosts addresses.
One will be your source server, and the other will be the target server.

Install Content Staging.
Installation steps are here: https://doc.ez.no/Extensions/eZ-Publish-extensions/eZ-Content-Staging/eZ-Content-Staging-1.x/Installation

Important: When installing eZ Content Staging 4.7.1 in the source server, make sure to use:

TransportClass=eZRestApiEmbeddedClientStagingTransport471

Create a new content class with the following configuration :

Name : Layout content sync
ID : layout_content_sync
Container : Not checked

Add one attribute (Text line)

• Name of the attribute : Title
• ID of the attribute : title

Add another attribute (datatype layout)

• Name of the attribute : Layout
• ID of the attribute : layout

Submit the creation of the class.

In a override of the block.ini configuration file define a new block as the following:

[LayoutContentSync]
Name=Layout content sync
NumberOfValidItems=1
NumberOfArchivedItems=0
ManualAddingOfItems=enabled

Add it to the AllowedTypes array, under the [General] block:

AllowedTypes[]=LayoutContentSync

In an override of the zone.ini configuration file, make sure that the "2ZonesLayout1" is avalable in [General] block :

AllowedTypes[]=2ZonesLayout1

Make 2ZonesLayout1 available for class layout_content_sync:

[2ZonesLayout1]
AvailableForClasses[]=layout_content_sync

Clear eZ Publish caches, then repeat all previous steps on the ez content staging target instance.

Steps to reproduce:

In the content tree create an new content "Folder" named "eZ Flow block source folder".

In the content tree create a new content object of class Layout content sync:
1. Add the title "Content sync object" to this new object
2. In the "left zone" zone add a new Layout content sync block, and give it the following name: "Issue test"
3. Click on Add item and select the previously created eZ Flow block source folder content object
4. Publish this new Layout content sync object
5. Launch the content staging sync for both the created objects Content sync object and eZ Flow block source folder.

Result:

Check the Target instance.
The eZ Flow block will be synced, but the eZ Flow block item (eZ Flow block source folder) will not be present in the block items.

Note: If we use TransportClass=eZRestApiEmbeddedClientStagingTransport the eZ Flow block item will be synced correctly.
The issue occurs when using TransportClass=eZRestApiEmbeddedClientStagingTransport471 only.