Hidden fields flashes and then disappear


I am observing some weird thing happening in the form where I have hide one of the field but as soon as I open the link to submit the form the hidden field flashes out and then disappear.

The function I used in JS to hide the contact id is as below :

fd.rendered(function() {
// Hide Contact ID field in form

Is there something I am missing or where I should look for to correct this problem?

Appreciate any help!

Dear @5by5,
When does it flash - on submit or when the form loads? What type of a field is it? Can you perhaps record a short video for us, if possible?