Thanks for your patience. Please let us know which file format you're trying to export. Also, could you share the Project URL with us and provide us with edit access to investigate further? You can either provide direct access or create a copy of it and then provide edit access.
Thank you for reply. I tried to download it as PNG (what I needed) and as JPEG just in case. It seems this problem occurs only with a specific type of projects with transparent background.
I don't have this problem with other projects
I need your email to share the project with you, right?