vbulletin 5.2.5 upload multi*byte filename problem

[idis]

when I uploading multi byte filename file, first multi byte character(korean or japanese or chinese) is disappearing
but start with English or number or special character, it' ok

e.g)
xxx=multi byte character(korean or japanese or chinese)
yyy=multi byte character

select upload file then changed filename is added upload attachment list
xxx.pdf -> pdf problem(disappear xxx and .)
xxx yyy.pdf -> yyy.pdf problem(disappear xxx)
123xxx.pdf -> 123xxx.pdf ok
abcxxx.pdf -> abcxxx.pdf ok
[xxx].pdf -> [xxx].pdf ok

this problem only occurs when first character is a multi byte character(korean or japanese or chinese)

my DB and server charset is utf8

I'm using chrome

[Wayne Luke]

This is a known issue due to how vBulletin handles multi-byte characters. We do not have a fix at this time. It is recommended not to use multibyte characters in attachment file names.