I have found two problems with FTB v18.104.22.1686 and the MyHeritage website.
(1) I created a family tree using FTB and a corresponding website for my wife's family, the O'Neils. When I tried to publish the family tree, the upload hung at 99% saying that it was waiting for the website to process the data. Strangely, I was able to export a GEDCOM file from FTB and import it into her website, I just wasn't able to publish it from within FTB. After many attempts to fix the problem, I finally concluded that the apostrophe in O'Neil was the problem. So, I edited the GEDCOM file from FTB by doing a global replacement of ONeil for O'Neil, opened the revised GEDCOM in FTB and was then able to publish to the MyHeritage website. I then edited the FTB tree to replace the apostrophes and was able to publish the revisions. So, the bug appears to be in the processing of uploads from FTB.
(2) I have 2 family trees created with FTB, one for my family and one for my wife's family. In my website, the tree cannot be edited, which someone told me was normal for a tree uploaded from FTB. This seems sensible, since there does not appear to be any way to sync the website with changes made in FTB. However, my wife's website can be edited by members. I looked around and found that the SETTINGS/PRIVACY/ADDRESS BOOK page had a check box to allow or not allow changes by members. However, the box was grayed out and could not be changed. Furthermore, box had no check mark in it, so how could editing by members be allowed?