We are running Windows 10 (Version 1909 - OS Build 18363.1854) and Office 365 Apps for Enterprise (Version 2110 - Build 14527.20276).
According to Microsoft's update documentation for September 28, 2021, Version 2109 (Build 14430.20234), Microsoft "fixed an issue where applying styles from the Home tab did not work." They did not state what was changed. After this Microsoft update to Office 365, the numbering in our custom Style Sets (accessed from the Design Tab on the ribbon) stopped working on the heading styles in a custom template. Prior to this update, we used the custom style sets, heading styles, and templates for 4-5 years without issue.
The following attached images show how it should look with the custom style set applied (from the Design Tab) to a custom report template:
-- CustomStyleSet_fromDesignTab.jpg
-- CorrectNumbering.jpg
The following attached image shows how the headings and bullet/number lists look after the update (Version 2110 - Build 14527.20276) with the same custom style set applied (from the Design Tab) to the same custom report template. I highlighted the "corrupt" areas.
-- CorruptNumbering_bulletlisthighlighted.jpg
Amongst many attempts to fix this in the updated Word, the following have been completed:
-- Copied quick style template with custom style set into C:\Program Files (x86)\Microsoft Office\root\Office16\1033\QuickStyles to test if file location affects performance:. This is where Microsoft stores the built-in style sets that are loaded with Office 365. I was able to paste the document in this location, however, the custom style set did not appear in the Build-In list (even after restarting Word).
-- Rebuilt custom style set in updated version of Word. Same "corrupt" results.
-- Opened blank document and applied the custom style set - the headings numbering and bullet/numbering lists worked. I then copied custom template into this blank document with custom style set applied and all numbering worked. Saved this new document as a new .dotx template and opened a new file based on this new template, applied the custom style set, and the same corrupt numbering shown above appeared with one difference - instead of the corrupt custom bullet list, the custom numbering list broke the same way. See the following attached image:
-- CorruptNumbering_numberinglisthighlighted.jpg
Since I don't know what Microsoft changed, it makes this very difficult to troubleshoot so any suggestions are greatly appreciated!