Excalidraw in Obsidian arrow moving with the linked shape

I’m trying to do a mind map using excalidraw plugin. Such a fantastic tool !
Sorry for such a basic question, but my arrows in excalidraw dont move with the linkind shape. I draw two shapes, and then an arrow from one to the other one, but the grey frame arround the shape doesn’t appear, and arrow doesn’t “stik” to the shape. I has worked one time, but now, no way.
Can you help me please

Could you share a screen recording? It would be easier to help you. Normally, grayed edges appear well before clicking to position the arrow. But there is often a small margin between the shape and the gray edge.

Thanks for the answeer Anwen.
I’ve juste found the solution. The trouble was … my screen settings ! To light to let me see the grayed edges. Hope it will help someone else.