Using the plug-in (latest version) in Reaper (latest version) I'm running into a few issues. After opening a file, selecting a bar then selecting "Bar Settings" or "Song Settings" toward the top right of the screen, the settings dialog floating window was showing up on my 2nd monitor, which I did not have turned on. Every time I open the bar or song settings the floating window is on my 2nd monitor (which is now turned on).
The first time, when my 2nd monitor was off I thought it was a bug given the rotating icon in the plugin that never stopped. While this might be a Reaper bug, when I went to close the FX dialog window, while the settings dialog was unknowingly on my 2nd monitor, Reaper crashed.
I had never used the plugin in Reaper so I'm not sure why the settings dialog would show up on the 2nd monitor to begin with.
(Windows 10)