Problem with Export Font

I’m using the Font Awesome Free font on my website. But I use only some few glyphs of it. So opened the

fa-solid-900.woff2

font file and deleted all unneeded glyphs:

Than I tried so save it as WOFF2, but I have to use the export feature of this: Menu: File → Export Font → Export as Web Font (woff / woff2).

There I selected this:
WOFF Version: Version 2
Outline Format: TrueType
Color: No
Open Type Layout Format: Yes
Hinting: Keep Original

… and to export worked fine: I can use the generated file inside my Webbrowser (Firefox and Chrome).

But if I reopen the file, I do not longer see all glyphs as well:

Additional the names of the glyphs are lost.

What do I wrong?

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