I’m having a somewhat similar problem with a runtime UDT. The UDT works fine but for some reason gives a bad tag quality reading but if i double click on the tag to edit it, then press okay the quality goes to good. each tag within the udt still maintains its value and operates the whole time as well.
I am experiencing the same issue. I was able to successfully create tags manually with my CLICK_PLC. Today all the tags became null, moreover the diagnostics tags (connectivity, port, IsConnected, etc) also are registering issues ([null, Uncertain_InitialValue,).
The Status Code on the OPC Connections shows good, the same as the Device connection, yet the Designer keeps showing the Null error.
Any idea on how to look for the logs describing the root cause?