why are table boundaries erased in sections

Writer 6.3 under Linux- Ubuntu 18.04
I create a formed table with boundaries in a section and then save the file. When reopened, however, the table has lost its boundaries. What is going on? Is this a bug?
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Works for me.

How do you create the table: table “styles” or Table>Insert Table? How do you save file: .odt (native format) or .doc(x) (or any other foreign format)?

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