In 1.16.1, Toolbars saved from the Saved Toolbars feature are empty, even if something was saved in them in prior versions. I put three screenshots off this, one from 1.12.2 (The one with more stuff, prior to The Flattening), one from 1.15.2 (The one with less stuff because of The Flattening), and one from 1.16.1 (The one with no stuff due to this bug).