I think this might be a clue (snip near the end of the log)
Code:
Windows: ('10', '10.0.26100', 'SP0', 'Multiprocessor Free')
Interface language: None
EXE path: C:\Program Files\Calibre2\calibre-debug.exe
Successfully initialized third party plugins: DeACSM (0, 0, 16) && Gather KFX-ZIP (from KFX Input) (2, 19, 0) && DeDRM (10, 0, 9) && Package KFX (from KFX Input) (2, 19, 0) && KFX metadata reader (from KFX Input) (2, 19, 0) && From KFX (2, 19, 0) && KFX Input (2, 19, 0) && Kobo Utilities (2, 18, 1)
Traceback (most recent call last):
File "calibre\gui2\__init__.py", line 806, in dispatch
File "calibre_plugins.koboutilities.action", line 2900, in _store_completed
File "calibre_plugins.koboutilities.dialogs", line 3774, in __init__
File "calibre_plugins.koboutilities.dialogs", line 3932, in populate_table
File "calibre_plugins.koboutilities.dialogs", line 4003, in populate_table_row
File "calibre_plugins.koboutilities.action", line 7906, in convert_kobo_date
File "calibre_plugins.koboutilities.common_utils", line 321, in convert_kobo_date
TypeError: strptime() argument 1 must be str, not None