Physics are having issues on DS or more has been changed
#1: many players on our DS have reported that during construction, now their hard work collapses more often than before and more often because of unknown reasons. i, myself experienced this, i had completed a smaller castle, logged out, 2-3 days later, i went back entered a hallway and boom, some pillars collapsed which held together for some time, than suddenly they broke.
i checked with CreativeMode and even there some prior possible constructions, now are not working anymore. The stress to some pillars is higher than before. Also the indicator does not tell players on DS the correct situation.
For example, you put 2 stone pillars on each other and on top an Arch outer corner, in CM the stress indicator (which is not available on DS), shows that both stone pillars are yellow (critical). On a DS the tooltip is confusing or wrong. The lowest pillar shows "light" and the pillar above "critical", some times even "exeeded". Even with exeeded, the construction is still standing sometimes. Then at some point the structure collapses.
When you build the same structural example with Log pillars, you get the same stress view which makes sense, but when you over do it, it collapses, but when you look at the broken result, the damage is not comprehensibly.
#2: To our impression the structure strength is linked to the hitpoints of the object, with some unseen modification. We tested on the DS, hitting a Log pillar and a plank pillar with a sword. What we saw is, that both pillar took exactly the same damage. Well i never tried to cut down a log with a sword or block or planks, but from our understanding, it should be harder to cut down a log than a block of planks, since the planks have a weakness along the length.
#3: by doing this test, we saw something interesting. comparing the 3 pillars, the log pillar has 800 hitpoints, the plank pillar has 600 hitpoints and to our surprise the stone pillar has also 600 hitpoints. Which is confusing, a stone pillar should have more strength.