In reply to Tom J Nowell.

I've had the exact same thing happen to me on several sites. It kicks the old content out the widgets, rearranges the content, and sometimes it appears as unusable inactive side content listed above inactive widgets. I am having several different situation happen in different sites using the same thing (Bridge by Qode) and in the worst cases, I can't get to ANY of the old widget content to reorganize. It just looks like it disappears. Sometimes it stays in the site, sometimes it doesn't. I agree with something I read above - I don't think Block Widgets were ready for primetime, and I disagree with the idea that you are forcing all users to rebuild this functionality Blocks. I personally have found Blocks to be terrible, I can't get behind that.