Sorry, another strange one. For every other project, the ability to work in split screen mode with the Main Editor and Other Editor works fine. However for one project (and an important one), when I go into Split Screen, then chose the Other Editor to make it active and then go to the Binder to select the document to open in the Other Editor, the document is placed in the Main Editor. I have tried this various time in this project and it always has this incorrect behavior. I can select the Other Editor to be active and the use the right and left arrowhead icons and the up and down arrowhead icons to change the document. And I can edit the document and scroll it, etc. I just cannot change it by selecting a new Binder entry.
Then I opened this project on the Mac, and the use of both Editors worked as expected. So it looks like it is project related, but that Mac and Windows treat it differently. After it worked on Mac, I then opened again on Windows, but still had same problem. Glad to zip the project and send to you. But have you run into anything like this before? I was doing some testing and bookmarking things, opening documents in Copyholder and Quick Reference previously, Locking Main Editor (not in split screen mode) in Place, then unlocking it, etc. and all that seemed to work, but not sure if some combination of testing things out somehow somehow makes my Other Editor think it is locked when I select a Binder entry, but not locked when I use the arrowheads.
Hello! Just to check, in the affected project what is Navigate > Binder Selection Affects set to? That option is project-specific so it may that it is set to something different than the other projects you mentioned.
Brilliant! That solved it. I was not even aware of that option, but somehow must have clicked on it inadvertently when viewing the Navigate menu and then somehow clicking on it. I tested it out and now working the way you would expect it to. Thanks for showing me that.