Can't write Unicode tags

[Bob Bib <bobbib ukr net>]

Configuration:
easytag 2.4.0
on
Debian testing amd64 (Debian package version: 2.4.0-2)

Preferences enabled ("ID3 Tags" tab):
Strip ID3 tags if all ID3 tags are empty
Write ID3v2 tag Version: ID3v2.4
Character encoding: Unicode UTF-8
Automatically convert old ID3v2 tag versions
Use CRC-32

Operation: tagging some files with Cyrillic symbols in data.
The resulting saved files contain garbage info in tags.

Sample Log excerpt:
===
01:21:20 Starting EasyTAG version 2.4.0…
01:21:20 System locale is ‘en_GB.UTF-8’, using ‘ISO-8859-1’
...
01:21:47 Selected files tagged with artist ‘Песняры’
...
01:21:59 convert_string(): Failed conversion from charset 'UTF-8' to 
'ISO-8859-1'. String 
'\320\237\320\265\321\201\320\275\321\217\321\200\321\213'. Errcode 1 
(Invalid byte sequence in conversion input).
01:24:31 Normal exit
===

Looks like it's ignoring tag character encoding settings, using the code 
table weirdly auto-guessed at the start time (and there's no obvious 
option to force Unicode mode on start); here's one more example:
===
02:34:56 System locale is ‘uk_UA.UTF-8’, using ‘KOI8-U’
===

So should I forward this information to the bugtracker?

--
Best wishes,
Bob