Styles Duplicating When Selected

[jamesh]

Hello all:
Windows 10, Office 365 (2019).
When I try to apply a style to text, the style is not applied and instead a new style is created. See image from a new word document. Imgur: The magic of the Internet No style template or anything.





In this image I attempted to set the style of the selected text to Heading 1 and instead a new style was created called Heading,1 with "normal" settings.

Once this happens, the text won't take other styles if I try to assign them.

Appreciate any help. Thank you!