Encoding -> Convert to Ansi will encode it in ANSI/UNICODE. Utf8 is a subset of Unicode. Perhaps in ANSI will be encoded correctly, but here we are talking about UTF8, @SequenceDigitale.
There are faster ways, like exporting as csv ( comma delimited ) and then, opening that csv with Notepad++ ( free ), then Encoding > Convert to UTF8. But only if you have to do this once per file. If you need to change and export fequently, then the best is LibreOffice or GDocs solution.