I bet you save your document as .doc(x). M$ Word is based on different principles than LO Writer. In particular, Word has absolutely no notion of character, page, frame and list styles. When the document is converted into this alien format, the style formatting is replaced by approximate direct formatting resembling as much as possible the original formatting.
When you reopen the document, an inverse conversion takes place. However since there is no frame style definition in a .doc(x), no frame style can be created.
What you describe as spurious ListLabel99 character styles is an indication of the conversion mess introduced by the round trip to .doc(x).
If you want to work with styles (I encourage you and congratulate you for that), which is the recommended way to work with Writer – and this brings real comfort when tuning formatting --, save your document as .odt.
CAUTION! Since your document has already been “damaged” by multiple conversions, your style dictionary is “polluted” by tons of ersatz definitions in a desperate effort of Writer to make sense with the formatting. To clean the situation, the best way is to create a fresh blank document and to paste your “damaged” file as unformatted text so that no “pollution” is carried over.
Then use the built-in styles to format your text and add the missing ones. Save always as .odt.
If you need to exchange your document with other people, note that M$ Word claims to be able to read ODF (though in its own somewhat incompatible way). In case, this doesn’t work, only export as .docx for exchange. Don’t import back. If there are corrections on the document, ask for them to be clearly marked so in order to type them yourself into your .odt.
You can also export as PDF which guarantees that your formatting will be unaltered. PDF export is a very good solution if the document does not need to be edited.
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