modification de champ

modification de champ

Hello
Since this morning when I want to modify a field (add item in drop-down list) in Zoho I do not arrive
I go in configuration, layouts and fields, I choose list of fields then I click on the button to create or modify a field and I have a blank page (without my fields): on the other hand at the top I have a red square which appears with an exclamation mark
You have an explanation
cordially