I found this bug on yesterday.
titlesec in latex document, the latex compiler (I use
xelatex) doesn't generate all section numbers.
This bug have been reported on https://bugs.launchpad.net/ubuntu/+source/texlive-extra/+bug/1574052.
The solutions are discussed in http://tex.stackexchange.com/questions/299969/titlesec-loss-of-section-numbering-with-the-new-update-2016-03-15.
You only upgrade the package version from
2.10.2 manually. The instruction is following below:
2.10.2from CTAN or you can download directly.
What about you? If this solution can help you, please share. Thank you