Ladder falls apart

I use a Nook HD software version 2.2.1

My home base has a ladder that extends from the original surface level down to the bedrock. This ladder falls apart.

I assume its something that is happening when I enter my base because every time I discover it, the pieces are still present - which means its within 5 minutes. This is the only ladder in the game that does this. I have to take a waterfall down to the bedrock and rebuild it from there. Sometimes half the ladder is still in place.

There have been times when I didn't notice it or look for it right away and I had to recreate the pieces because they were lost.