Capturing UTM Values for Known Users on Webflow

[agolove]

I am trying to capture UTM parameters of form fills regardless if the marketo engagement is a known visitor or not, without using Smart Campaigns to write to the UTM fields on Webflow landing pages. This function is currently working on WordPress landing pages. 

Our forms have hidden fields set up and work for new users and on WordPress landing pages for known visitors. On Webflow landing pages, the UTM values are not writing for Known Visitors. We are using the recommended JavaScript (thank you @SanfordWhiteman) workaround  (https://nation.marketo.com/t5/product-discussions/how-to-add-utm-parameters-to-quot-known-visitor-qu... aka https://codepen.io/figureone/pen/jOWVZMg (CodePen Home MktoForms2 :: Auto-Fill w/Cascade v1.1.2) to our pages. 

On Webflow landing pages this recommended JavaScript workaround is a partial success, as the values are stored, but the hidden field values are not being written without use of a Smart Campaign. 

Is there an extra step needed on Webflow landing pages so that the UTM Fields are written to for known visitors without a Smart Campaign?

[SanfordWhiteman]

I don't understand what you mean by "stored" vs. "being written". That JS only updates hidden fields, it doesn't have different modes.