OK, I have not seen anyone post about this. There are random times while hunting that my % weight will jump to 100%. I could be fine at like 51% and even without a drop it runs up to 100% which sucks when you are in a daily because you cannot restart without losing the daily run. So, I have to drop stuff and try to get under weight to attack.
This weekend, I was hunting and took no items off and went from around 200% MR to 12% then taking off and putting back on pieces, I actually got to -12% MR. Very very random. Others said on global they had seen that before. Sucks when you are fighting something with magical attack. There is no appearance of a debuff or anything like that.
Very random, and very annoying. I have had the weight thing happen more frequently than the MR drop.