What version of MS Word are you using?, not the revision number but the main version (MS Word 2007, MS Word 2010, MS Word 2013, MS Word 365... How are you generating the list? using embedHTML, addList or a template?
We have tested the lists using the latest revision of MS Word 2019 and the output is correct in all cases, but doing more tests we have checked that the latest release of MS Word 365 has added a maximum value to numId in lists that doesn't fit OOXML standard. We are doing more tests, please post the MS Word program you are using (MS Word 2007, 2010, 2019, 365...)
Please send the DOCX to contact[at]phpdocx.com so we can check it with all versions from MS Word 2007 to MS Word 2019, MS Word Online, MS Word 365 and LibreOffice.