Reloading a .docx file with empty Table of Contents makes it go away and introduce a new, stange-named style.
Steps to Reproduce:
1. Create empty document
2. "Insert" -> "Table of Contents and Index" -> "Table of Contents, Index or Bibliography"
3. In the dialogue press "OK" to create a Table of Contents.
4. Save the file as "Word 2007-2019 (.docx)".
5. Close the document and open again.
1. The ToC is gone.
2. New "TOA Heading" style is added to the list of ToC styles.
1. ToC is still there, despite being empty.
2. New style is not created, but default "Contents Heading" style us used.
User Profile Reset: No
Expected results can be observed when saving to .odt instead of .docx.
Build ID: d6e8e41c22023bc15cc4c9659b33c1cc3d6edb75
CPU threads: 4; OS: Windows 6.1; UI render: default; VCL: win;
TinderBox: Win-x86@42, Branch:master, Time: 2019-05-05_23:45:44
Locale: ru-RU (ru_RU); UI-Language: en-US
Looks like ToC never was saved OK so I'll put Inherited.
New "TOA Heading" style was added later.
But this is special case so I'll mark minor.
Created attachment 167676 [details]
Example file to reproduce the problem
Still present in:
Version: 184.108.40.206.alpha0+ (x64)
Build ID: f7e2f5bca938aa916830e07895d2da6820282055
CPU threads: 4; OS: Windows 6.3 Build 9600; UI render: Skia/Raster; VCL: win
Locale: en-US (hu_HU); UI: en-US
Adding a new paragraph with Heading 1 style and updating the TOC in odt puts the new paragraph into the TOC but this is not possible if this file was saved as docx.