I’m going through the same issue, FYI.
Have created new Collection fields, new Collections entirely and new Zaps. Nothing has worked.
About to test out the integromat option. Will let you know how it works.
Edit: Didn’t need to test integromat. I watched the video @johnematias recommended and it worked. My issue was that I was not referencing the CMS ID of the rollup items, I was referencing the CMS name. I changed to referencing the ID and it worked.