Try to parse attached file
test.zip
LibreOffice and all other known to me editors correctly opens it

But parsing it with ruby-rtf result are:
require_relative 'lib/ruby-rtf'
rtf = RubyRTF::Parser.new.parse(File.open('/home/lobashov/temp/test.rtf').read)
rtf.sections.each do |sec|
puts sec[:text]
end
Outpus (ignoring warnings about unknown control):
Tested on ruby-rtf v0.0.5 with ruby 2.7