Hi!
Both subsync -2000 -o "C:\\test.srt"
and subsync -2000 -w "C:\\test.srt" "C:\\test.srt"
(And subsync -2000 -o -w "C:\\test.srt" "C:\\test.srt" as well)
only seem to generate 1-byte files with the character ÿ in it.

Writing to a new file seems to work fine.

Windows 10 x64