I have been Googling and trying anything + plugins I can find on Google, but none of the things I tried fixed my issue.
For some reason, when I go to my URL/category --> Works URL/category/subcategory/post.html --> works URL/category/subcategory --> DOESN'T WORK (https://businessanddata.org/excel/excel-general/)
For my permalink, I am currently using the custom structure as the screenshot is showing. I have check Yoast settings and don't see anything out of ordinary. The URLs were working before the version 4.9.4.
Any help is truly appreciated!