Thank you very much,
I did another try and it still doesnt work. Was exporting output as JPEG file with 'Embed metadata' unticked as suggested.
I dropped '.afphoto' file to the dropbox.
But after that I did another experiment.
The process I followed was: I exported 2x 360 panoramas from PTGui. One as JPEG and one as EXR.
Jpeg loaded to FB works ok. Loaded to PS, tweaked and exported also is being read in FB as 360 panorama. When I imported JPEG into Affinity and reexported it back it was also read as 360 Panorama by FB. So it means that Affinity works fine.
I expect that exported from PTGui EXR file had never any 360 metadata so it has not been removed. But unfortunately it means that when I import any 360 EXR/HDR Panorama into Affinity Photo for tweaking it will never get 360 tagging/metadata to work in FB etc.
Is there any chance to have it added as an export feature, or maybe there is a way to add it somehow in Affinity already?
The workaround I found is to export 360 Panorama file as JPEG and EXR file from PTGui, do all tweaks I need on EXR in Affinity, export it as JPEG and copy it into the memory, next Open the exported from PTGui file which had correct metadata included and paste tweked JPEG into it, collapse layers and resave it.. and this way it works
Thanks in advance
GrzegorzB