Indesign v17.1, Windows 10
Problem: when opening a second document while the first currently is on page 22, for example (see screenshot), and then tiling, the 2nd document is shown to be on page 22 as well, though it's not. With the 2nd document being on master page C-Rear EA, the page selector not only shows 22, it also has the checkmark put next to 22 when you open the dropdown.