[....]

ABC_DEF123_IJK_V5_V.xls

?

There does come a point at which if enough humans are allowed to
throw
enough random character variations at a computer, the computer won't
be able to detect any pattern.

Ack
sometimes it's just not possible to parse such differing strings :-)

For the OP: For the future you may consider defining some name
conventions for your filenames (and maybe even restrict them). As
Harlan said there's a point completely free user entries will mess with
any type of formula/code :-)

Frank