Table Style - Top Left Cell

I have the same issue (04/03/2026).  I can fix it on an individual basis by selecting the table and pressing Ctrl+Space to clear formatting, then reapplying the custom style.  But, like the OP I want the core problem solved.

In my case, there is a wrinkle:

Create a table -> enter text into top left cell -> apply table format = everything works

Create a table -> apply table format -> enter text into top left cell = text in top left cell is black

The problem only seemed to arise after I set a coloured table style as default, triggering Word to apply that style before the table had any contents.  It seems to be a one way street though, and now I have the problem I can't get back to how things were.

I have confirmed by using a second machine.  I could apply a built in coloured style to an empty table and it worked as expected.  After setting a coloured style to default the problem appeared.  Having reset the default style to the base built-in style, BOTH machines now exhibit the problem.

I've been round and round and round with web searches and LLM's to no avail. 😭😭😭