P: Save As PNG format deletes all metadata

Photoshop 2020 (21.0.1) I posted this problem on the Adobe Support Community forum on Nov 8, with no resolution (original post). I also emailed Adobe Care but after one irrelevant response they are ignoring me. So I am trying the same post here.

Original post:

My Photoshop workflow is: Add metadata as a sidecar file to the NEF raw file (using ACDSee); open NEF file in Photoshop camera raw; do some edits; open image; save as PSD; do whatever to the image in Photoshop; Save As .png format for Web use. In Photoshop 2019 this retained all metadata and saved it in the .png file. In Photoshop 2020 this deletes all metadata - EXIF, IPTC, GPS data, camera data, everything except the Photoshop-specific tags. Doing the same but saving as JPEG retains all of the the metadata.

When I installed the 2020 update I retained the Photoshop preferences, but removed the 2019 version.

In Photoshop 2020 all of the metadata is visible in File -> File Info, and is saved in the .psd files (i.e. visible to external programs like ACDSee). I can also export the XMP file from File Info and all the data is there. It's just saving as .png that loses the metadata. Export (both Quick Export and Export As) as .png also loses the data.

This makes Photoshop 2020 useless for me, since I don't want to save as JPEG. I have re-installed Photoshop 2019, and it works as it should.

What is going on here??? Is there some setting I need to change in Photoshop 2020 to get it to save metadata in .png files? Or is this another bug?

Note: Windows 10 (latest), Photoshop 21.0.1 update.

David