Yes. I can edit the original AZW3 without issue and see the same things you're seeing with Tools > Check Book. OTOH, EpubCheck has fatal issues with the book. Running that gives an error dialog with the following details:
Code:
calibre, version 6.10.0
ERROR: Unhandled exception: <b>AttributeError</b>:'OptionValues' object has no attribute 'dont_compress'
calibre 6.10 embedded-python: True
Windows-10-10.0.19045-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.19045')
Python 3.10.1
Windows: ('10', '10.0.19045', 'SP0', 'Multiprocessor Free')
Interface language: None
Successfully initialized third party plugins: DeACSM (0, 0, 16) && DeDRM (10, 0, 3) && Diaps Editing Toolbag (0, 4, 0) && EpubCheck (0, 2, 4) && EpubSplit (3, 5, 0) && Goodreads (1, 7, 1) && KindleUnpack - The Plugin (0, 83, 1) && Kobo Utilities (2, 16, 6) && KoboTouchExtended (3, 6, 3) && Modify ePub (1, 8, 1) && Quality Check (1, 13, 3) && ScrambleEbook (0, 6, 0)
Traceback (most recent call last):
File "calibre_plugins.epub_check.main", line 221, in ask_user
File "calibre\ebooks\oeb\polish\container.py", line 1543, in commit
File "calibre\ebooks\oeb\polish\container.py", line 1470, in opf_to_azw3
File "calibre\ebooks\conversion\plugins\mobi_output.py", line 328, in convert
File "calibre\ebooks\mobi\writer8\main.py", line 496, in create_kf8_book
File "calibre\ebooks\mobi\writer8\main.py", line 45, in __init__
AttributeError: 'OptionValues' object has no attribute 'dont_compress'