I just started having an issue today in some of my workflows where I can't edit the python code within the python tool. I can edit it just fine in some workflows, but in others I can not. On the workflows where I can't edit the code, it also seems like the code I can't edit is disappearing when I click out of the tool, then I have to control Z to get the text back, or open and close the workflow.
Version: 2021.4.2.47792 designer
I can edit other tools in the workflow. I get the same error with the python tool if I bring in a new python with no code, it still doesn't let me add any code/text to it.
since version 2019.1 I have problems with the python tool with this type of error you are pointing and another error when opening the tool 404 -
I write my code in notepad++ beforehand and generate a backup version; and when these errors happen I put a new tool and insert the python code again...
is what I can collaborate on your problem