I found the 100 character restriction in /modules/blockreassurance/views/js/back.js and changed it to 500. My text is visible again.
// Tab Content : Edit : MaxLength
$(document).on('keyup keydown', '.show-rea-block.active .content_by_lang input[type="text"], .show-rea-block.active .content_by_lang textarea', function () {
var maxLength = 500;
var val = $(this).val();
var valLength = val.length;
if (val.length > maxLength) {
$(this).val(val.substring(0, maxLength - 1));
valLength = $(this).val().length;
}
if ($(this).is('input:text')) {
$('.limit_text:visible').text(valLength);
} else {
$('.limit_description:visible').text(valLength);
}
});