Subdirectories in OMEX files not working

[luciansmith]

Following some example code, I grabbed thumbnail images from pubmedcentral and added them to OMEX files, a la:

        if citation.pubmed_central_id:
            thumbnails = get_pubmed_central_open_access_graphics(
                citation.pubmed_central_id,
                temp_entry_dir,
                )
            fileList = glob.glob(temp_entry_dir + '/*.tar.gz')
            # Iterate over the list of filepaths & remove each file.
            for filePath in fileList:
                os.remove(filePath)
            metadata['thumbnails'] = [os.path.relpath(thumbnail.filename, temp_entry_dir).replace("\\", "/") for thumbnail in thumbnails]

Unfortunately, the resulting OMEX file does not load on run.biosimulations, cf

https://run.biosimulations.org/runs/642b2afcf408510872c7b81a#tab=log

There was an error creating thumbnails for the project. Please ensure that the images specified in the manifest are valid. A validation tool is available at https://run.biosimulations.org/utils/validate-project.
Process the metadata in the COMBINE archive ... failed:
There was an error in processing the metadata file. More information is available at https://docs.biosimulations.org/concepts/conventions/simulation-project-metadata/. A validation tool is available at https://run.biosimulations.org/utils/validate-metadata.
Post the metadata to the API ... failed due to a dependent step failing.
Read the manifest and post the files to the API ... failed:
There was an error uploading file metadata to the API. Please try again and contact us if the problem persists.

BIOMD0000000026.zip