Vi: Upper case umlauts not displayed correctly

if i cat the file input.csv, umlaut are displayed correctly

Output

XXXX
os|Äng
XXX

however with vi or vim, following characters are displayed ▒~D

Output

XXXX
Ebénist
Moos|▒~Dnge
XXXX

All lowercase umlaut work file , its the uppercase that are not displayed correctly

file encoding is:

file -i input.csv input.csv: text/plain; charset=utf-8

LANG=en_US.UTF-8

rest all locale value="C" also tried with LANG=de_DE.UTF-8 Any pointers will be helpful