I was running into problems where I would add some tags (6 of them) and I would add a seventh tag and all of my tags would get a little green symbol.
I would then delete the six tags I previously added and re-add the seventh tag, and it would be fine.
Frustrating.
It turned out to be an issue with the Siemens driver (v3.8.3) in which IA is currently working to resolve.
I fixed my problem by monitoring less data (I had a few large 256 byte strings that I stopped looking at).
String Path: ns=1;s=[PLC_Siemens]DB5500,string52.5
.5 limits the length to 5 bytes.