Quick Portal Manager in Real Time Monitors works only intermittently

Quick Portal Manager seems to work fine during session editting. It does not always work while driving trains. While in driver mode, there is a pull down menu marked "Run Time Monitors". Within that, there is "View Portal Manager". Most of the time, I can access the portal manager and do things such as tell a train to emit now. There are times, when the portal manager is not available and only a very simple window appears instead of the full portal manager window. I cannot figure out when or what makes this happen. Often, I can just save the game and exit, then begin again, and it works. Is there anything I can do to make the portal manager work regularly?

Thank you for your help.
I have the same issue in build 123794. The author, pguy, is aware of this, citing the age of the asset. He is looking to issue an update but he is not sure when this will be yet.