A few days ago I noticed my Bone Golems would randomly choose to not attack a spire in an echo. I opened a bug report in game for that, but decided to put something here because a bigger problem happened, and it may be happening to others: Just now they were refusing to attack the Reign of Dragons Timeline boss.
I’ve noticed that sometimes (but not always) I can get them to start attacking again by either running very far away and coming back to the spire, or sometimes recasting a new Bone Golem will trigger the others to start attacking again. The former isn’t possible with the Reign of Dragons Timeline boss, and the latter doesn’t always work. Fortunately I was able to live long enough to recast two new Bone Golems before they started attacking again.