Adobe Acrobat Pro DC - UI Bug in PDF Portfolio Panel for initial documents contained in subfolders
Product File Version is: Adobe Acrobat Pro DC 22.001.20117.0
When selecting a document from a subfolder of a portfolio as it´s initially shown document. (Collection Dictionary - COSName D)
(via: PortfolioProperties - "Show current document when opening portfolio") the folder navigation is missing when reopening the portfolio, hence preventing to navigate the portfolio in direction of the portfolio´s root.
Selecting such a document should be allowed and possible, as any entry of the EmbeddedFiles tree may serve as the "D" entry of the collection dictionary, hence it is correct of Adobe DC to allow me doing that.
And the selected document indeed is shown, when reopening the portfolio.
The issue is the missing "back" arrow at the top left of the portfolio panel. Adobe DC seems to be treating the containing folder as the "root" of the portfolio, when it clearly is not.
Adobe Acrobat Reader DC (2022.001.20117) is presenting the same issue for such a portfolio document.
Unselect the shown document and use "Open Folder" which redirects you to the actual "root" of the portfolio, from where you will be able to navigate normally.