One place that you can potentially lose the type anchor you mention.
I was with my friend in his boat fishing in the Mississippi river.
On the bottom of the river there are numerous pipe lines, cables and other misl stuff on the bottom of the river that runs from side to side in different places
At any rate, we were fishing one day and wanted to anchor on a wing dam so I dropped his anchor where he suggested. We had fished for a bit, and then decided to move.
I went to retrieve the anchor and it was a no go.
No matter how we backed up the boat, around and back and forth, the anchor stayed hooked up. It felt like the anchor had hooked up and was under an under river cable or pipeline. i.e. I think that as the anchor slipped down, it landed on the bottom and then slipped under the cable before hooking up. So, the anchor was actually hooked on the wrong side of the underwater obstruction. I could lift the anchor a couple of inches off the bottom, but that was all. So, I took out my knife and with the boat directly over the anchor, we lifted as high as we could lift the anchor, then, I reached down under the water as far as I could reach and cut the anchor line. The anchor line was nylon so would not float and be a navigation hazard. But we wanted to minimize the length of any anchor line that we left in the water.
I felt responsible for dropping the anchor in a spot where it could not be retrieved so I went out the next day and bought him a replacement anchor that was identical to the lost anchor.