Truly, it is shocking. How are they so bad at this?
I have 3 Apple devices right next to each other and the chance that all three of them will have the same set of items on the Safari Reading List is essentially nil. And there is no way to tell any of them to reload it.
The thousands and thousands of pages of people offering cargo-cult advice for how to fix this ricochet between "have you tried rebooting" and "turn off iCloud Safari sync then turn it back on" but all that does is make all of your reading list items and bookmarks disappear from that device and never come back.
It's one bookmark, Michael, how long could it take to sync? Ten years?