How to unlock cards in corkboard ?

I just saw I can’t move cards anymore inside my corkboard. I checked the OPTIONS box, but I found nothing about it…
How can that happens ?
Thanks ! +

If you select multiple items in the corkboard, you usually can’t move them. If you select a folder in the binder that contains sub-documents, then you can move those around, but not if you select multiple things in the binder.

Also, you can’t rearrange cards in a search-based collection, where you started out by using the search dialogue in the toolbar.

Mmh, OK. I thought it was something like that but I could’not find the logic.
Thank you,