Character missing in exported TTF file

Hi, I need some help.
I’m making my own font, although I’ve filled character A-Z.However, when exporting to TTF file, there are always several missing characters, and the missing characters are not consistent each time.
For example,Missing char B and V this time, the next export may be missing A and X.Although I didn’t modify the FCP file.
Attached is my original FCP file.
Lark20210430-153947.png
ARACHNE_DEMONIC_Blod.fcp (30.3 KB)

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