I don't know why the bullet symbol disappears. It might be a sign of a corrupt font, or (as you suggested) document corruption. Have you tried copying content into a new, blank document and recreating the formatting?

As far as the indentation is concerned, note that you should always define indentation for numbered and bulleted styles as follows: Apply the style to text. Click the bullet symbol to select it. Right-click and choose Adjust List Indents from the context menu. Make the desired changes. This should update the style, but just in case you may want to right-click the paragraph and choose Styles | Update <style name> to Match Selection.

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional