It took a long time but it finally works! It was indeed necessary for the super-admin to disable the filter "filterxsshtml" (which was not the case). However, I didn't have to disable the LimeSurvey settings of my question as recommended by tpartner here:
www.limesurvey.org/forum/can-i-do-this-w...th-percentage#144097
On the contrary, I had to leave the parameters as I had set them for it to work.
Thank you all!
