I have had this in middle of a whale base with a ton of loot, lost all of it.
Mine would have to be self inflicted, mostly when attacking in clan war and getting close to the three star have only a few buildings left and my troops manage to find that one trap that was left and I end up with a 99% attack because my troops went looking for a way to lose.
Being given the wrong troops when requesting something specific for war and either having to blow them or wait for ability to request again so I have to hold off on war attack.