I would say this was broken somewhere after 8.0.10. We didn’t notice it until we started using 8.1. Luckily we haven’t pushed 8.1 into production yet or this would have broken most of UDT based tags.
The problem comes in when you try to set one of the parameters on the nested UDT to one of the parameters for the next level up UDT. If parameters on both UDTs have the same name it seems to find the parameter value of its own parameter rather than looking up a level. This example is kind of messy as I was tearing things up to find out what was going on. But you’ll see the ThisTag parameter in MotorStarter_Alarm should be an empty string.
