I'm not sure if you are executing a static stored procedure or scripts, but maybe the text is not correctly encoded when saving to disk. I ran into this and my problem was resolved in PowerShell by correcting the SQL encoding that I saved on disk for osql processing:
Out-File -FilePath "MyFile.sql" -InputObject $MyRussianSQL -Encoding "Unicode" -Force; & osql -U myuser -P password -i "MyFile.sql";
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