Interacting with WebForm Update

This is an extension of ticket: https://developer.maximizer.com/discuss/65cfbea06a72de0010f0fbde

I'm trying to use a form to UPDATE a contact.

I get this error upon form submission:

We're sorry, the form that you have submitted is invalid or no longer exists.

Is there a way for me to troubleshoot this issue? I've compared every field in my form with the one generated by the form builder, e.g. U168I1259 on the generated form and on my form. I'm submitting to URL with the provided token from the builder, e.g.:

https://caw.maximizercrmlive.com/Webform.aspx?request=submitwebform&token=0954555742411A406D0B4740154E4024151C0D664A3C6F3C7A151D785C79720B18545F45404D436659425A5D783A043C69

I'm also pre-querying the API to get the ID and contact to do the update:

https://caw.maximizercrmlive.com/Webform.aspx?request=submitwebform&token=0954555742411A406D0B4740154E4024151C0D664A3C6F3C7A151D785C79720B18545F45404D436659425A5D783A043C69?id=240318251747349010012C&contact=0

(by the way, I don't get a contact Value in the CRM):

There's no "colon" like provided in the other ticket.

Any help would be appreciated.