A yellow alert icon is displayed in the Block Editor if a dynamic block definition contains errors or is incomplete. You need to correct the errors (or complete the block) so the block reference will function properly in a drawing.
The yellow alert icon indicates that the block definition is not defined correctly or is incomplete. For example, a parameter that is not associated with an action will display an alert icon. An action that is not associated with a parameter or a selection set, will also display an alert icon.
You can correct these errors by double-clicking the yellow alert icon and following the command prompts.
After you create a dynamic block definition in the Block Editor, you should save it and then test the functionality of the block reference in a drawing. If the block reference isn't functioning the way you intended, open the definition in the Block Editor and double-check the types of parameters and actions you used as well as their dependencies and properties.