Just in case someone at Siemens is listening, same problem just happened to me. Cut, compile and paste worked.

I guess an issue with an easy workaround doesn't require a solution.

TIA Portal v16 Update 1.

smiffy

I did a search in google and came across this thread of this forum.
https://www.automation.siemens.com/tf/WW/en/Posts/91968#T547048

I followed @James Brauer advice and copied the network and deleted the old network and it then compiled fine. So the EXACT same code copied into a new network compiles with no changes. Why?
Another bug I guess.
I suppose I could raise an SR to tell them about it. But my experience with this is that they simply tell me that what I have done is the workaround and have a nice day.

I have raised many SR's pointing out improvements / bugs / documentation errors and they just go into a black hole. How do we as users improve the product if we don't have a way a reporting issues to the developers? If I were a developer (and I have been in the past) and someone broke my compiler, I would insist on seeing the code and get to the bottom of why it had happened. No only for quality purposes, but for a interest / curiosity and professional pride point of view.

 I had the same issure today 28 Dec 2020 with TIA 15.1 update 4. the problem isn't solved yet. 

I deleted the network that contained the error, complied and inserted a new network with the same code. That solved it in my project. 

Hope this helps

Thank you, this last post helped me too. 

Just copied the same network and paste one network above and then it worked.