Placed a box into canoe on land - box invisible

I had a canoe laying on the dry ground, bottom up. I was carrying a wooden box. I have placed the box in the canoe by right-clicking the canoe. I lifted a canoe, carried it to the water and placed it on the water. Now the problem begins:
The canoe acts like the box is there:
- I cannot Pick Up the canoe, only lift it. When I right click the canoe, I enter it, no Pick Up action is offered
- I cannot place another item in the canoe
The box cannot be taken out:
- there is no box visible
I am not much concerned if I lose the wooden box, it contained just some stones and similar cheap items anyway, but I hate to have my canoe unusable. Is there anything I could do to get the "invisible" box out of the canoe now?
The canoe acts like the box is there:
- I cannot Pick Up the canoe, only lift it. When I right click the canoe, I enter it, no Pick Up action is offered
- I cannot place another item in the canoe
The box cannot be taken out:
- there is no box visible
I am not much concerned if I lose the wooden box, it contained just some stones and similar cheap items anyway, but I hate to have my canoe unusable. Is there anything I could do to get the "invisible" box out of the canoe now?