Why is Adobe not recognizing timestamp when SignedAttributes are present for a Signature ?

[Guest]

Hello

We successfuly sign and timestamp documents with itext.

The signatures are valid in Adobe Reader DC 2015.020.20042.

For most of our signatures with timestamps Adobe also displays timestamp informations.

But for a signature with SignedAttributes the Reader states "Signing time is from the clock on the signer's computer".

The CMSSignedData contains the Timestamp as UnsignedAttribute and we are programatically able to extract it.

Are the SignedAttributes a possible cause to let the Reader fail to recognize a timestamp ?