Windows 11 basecamp not showing route menu

Not quite sure what you mean by route menu, do you mean route properties? If so it works fine for me. Try an uninstall then reinstall of BaseCamp 

Assuming it is the route properties window, I don't have the problem on a Lenovo with similar specs and but running Win11 23H2.  Do you think you were on 23H2 when you last used it?

Yes, I should have said the properties window/menu. I have been busy and wasn't working on the problem. I tried to uninstall BC from the Windows 11 settings menu> installed Apps, but it still opened. I looked in the Control Panel> Programs and it wasn't there. It also wasn't in the Apps list in W 11 settings. I then reinstalled BC and still had the same problem.  The properties menu still didn't display.  I also have another Win 11 Dell with 24H2 and installed BC on it and it worked normally. The computer I primarily use is a laptop with two external monitors connected via a HDMI dock and I have then set to extend. I then unplugged the external monitors, and the route property menu appeared.  I reconnected the external monitors and the menu remained open and showed up on display 3. I could open and close the menu without problems on any monitor.  However, if the menu was on display 2 or 3 and I closed BC, it wouldn't appear after reopening BC. If I close BC with the property's menu on the laptop screen (display 1) it will work properly.  If I have BC open in display 2 and the property menu open on the same display, I can close, and open BC and it works.  However, if I have BC on display 3 with the property's menu, and now close and open BC, BC opens on display 1 and the properties menu doesn't appear.  Yes, it's weird but I have no other explanation.

I'm glad you figured out what was going on.  I work with a different program that has the same multi-monitor issues in that windows will open off-screen when the monitor they were last on is not available.  The program records last window placement using coordinates which become invalid.