I can't edit Formula tool, can anyone help?

[JessieHKSH]

 

[KGT]

Is it happening for all formula tools? If you close the macro and open it back up again, does it work?

This is a display issue with the HTML interface, when it used to happen occasionally, it was just a matter of trying again, sometimes restarting and was related to a system configuration with a specific display package (started with C, but can't remember the name). If it continues to occur, I would need to see the XML of the workflow to troubleshoot further (a copy of the macro), but if it's happening on multiple workflows, then support is going to be the best avenue.

[caltang]

Can you try opening the XML of the macro and find Formula (26)? Does it have any expression?

[mkeiffer]

I would try to delete the Formula Tool and put it back on the canvas.  If this doesn't work, then maybe try changing the macro back to a regular workflow and then see if that resolves the issue and then change it back to a macro. 

[dreldrel]

Try to recreate a new formula tool and reconnect it again. Sometimes it happens to me as well