Is the limitation reported and confirmed in this thread still present in the Media SDK version 20.3.0?
We checked the Intel® Media Software Development Kit 2020 R1 Release Notes and found the below line mentioned in the known limitations section.
"H.264 encoder in software implementation doesn’t support processing of mfxExtPictureTimingSEI template."
You can download the latest release notes from the below link
For H265,we didn't find anything related to that in release notes.So try from your end and let us know.