Security/sensitivity labels for PDFs in Sharepoint

I am trying to configure security/sensitivity labels for PDF's in Sharepoint. 

I initially followed Adobe instructions to enable MPIP in Acrobat which enabled the application of labels.

https://helpx.adobe.com/au/enterprise/kb/mpip-support-acrobat.html

That was followed by running a Powershell to enable PDF sensitivity labelling.

https://learn.microsoft.com/en-us/purview/sensitivity-labels-sharepoint-onedrive-files

I am now able to apply/update labels in Sharepoint for PDFs which is great however if I apply a label within Acrobat and upload the file into Sharepoint the label does not appear as metadata. Is this the expected behaviour?

If I download the PDF and open it in Acrobat, the label is still attached.  

My assumption was that if a label was applied in Sharepoint and viewable in Acrobat, the reverse would also work.