Transition rules get read-only and variables errors

Hi, I’ve a problem sometimes with my animation BP. Some transition rules get read-only And their content contains error Compilation: 0 error, but not functionnal finally To resolve that, i have to delete the transition and rewrite exactly the same. But i’ve a lot of transitions… it becomes totally not usable…
Here is an example of what i found in my transition:

But variables exist - if i delete the rule and rewrite it, exactly the same, it functions!
Could you help me ?