I am aware that there is a Trainz Plus update but my Trainz Plus installation is not showing that one is available when I click the Check for Trainz Updates button. See this screenshot:
Apparently the clean install of Trainz Plus build 119450 did not correctly set the target for future update streams. I had to click the "Change Targets" button and point to the actual TRS22.exe file itself, not just the folder, before Trainz would recognize an update was needed. Keep in mind that I made no changes at all to the base installation after the clean install so I see this as a glitch made during the Trainz Plus build 119450 installation process.