@robski :
Edit:    The address conflict is not with the ENV IV units, but with something else - either way I must remain on UIFlow 2.
I checked with two additional controllers:  Atom matrix, and  Stick C plus : The same issue.
However, odly I am able to "fool" the controllers for a brief timeperiod by going through a very particular sequence in Block editor:
add a PaHUB with some other sensor unit assigned to it in channel 0 of the HUB,  and run the script - ALL OK
Physically replace the sensor (channel 0) on the HUB with the thermal unit, but assign it directly to the i2c bus, and run the script  - ALL OK
Add several other sensor unit to the Pa.HUB (but keep the thermal unit assigned to the i2c bus, and run the script - ALL OK (runs several times without an issue, and all sensors respond correctly)
After saving the project and relaunching UIFlow 2, the script does not run, with this message:  "Thermal unit maybe not connect"
Quite confused by this.