I get with the files pdfa_article_v11.pdf and PDFExportDialog2.pdf of the "unclear" part of the Bavaria test suite. The cause is text like this in a PDF:
In a comment to PDFExportDialog2.pdf, pdflib tells "Unclear: hexadecimal string with whitespace characters (ambiguous in ISO 19005-1)" and "PDFlib opinion: whitespace in hex strings should be ignored". The PDF-Tools validator says it is a valid PDF. Solid Documents is unable to process the file.
Maruan Sahyoun do you know if this has been clarified in PDF/A-2b or PDF/A-3b? It is valid in "ordinary" PDF files.