I am experiencing a character encoding issue (mojibake) when importing a specific Japanese string.

File Encoding: UTF-8 with BOM

WordPress Database Collation: utf8mb4_unicode_520_ci

The issue is very specific:

The string "焼酎" imports correctly.

The string "甲" imports correctly.

However, the combined string "酎甲" gets corrupted during import.

This suggests a parsing bug in WP All Import when these specific character byte-sequences are adjacent. I have already tried all standard troubleshooting steps (checking file encoding, using functions.php filters) without success.

Could you please investigate this issue?