2 separate bones interfering

I have a 4 different scenes separated on the timeline in this project, and I’ve managed to use the bones without problems in the 3 prior; but for the fourth one I’m doing right now, for some reason when I add a third bone, it’s fine at first, but as soon as I try to position it the second one seems to break weirdly, by moving to a totally different position and messing up the whole sequence (to clarify, when I mention one bone I’m talking about the whole chain for one particular item). I haven’t had this happen before so I’m at a loss; the other 2 bones are for the arms, one of which has a hand with a kinematic attached to it. I feel like it probably has to do with the kinematic, but the hand is within the arm’s bone and works fine otherwise, so I don’t know why it would affect a totally different layer. I’ve tried separating the arm with the kinematic and the new bone further into separate pegs, but I still get the same problem. As soon as I click the rigging tool for the new bone, the arm moves to a totally different position, but the other arm is unaffected.

I’m still pretty new to this program, so it could be something really simple, but I’ve tried everything I could think of with my current knowledge of Harmony and couldn’t find anything online, so I’m pretty stumped. I put together some screenshots to articulate what happens when I try to do this.

It’s best not to have multiple scenes in one file. You can save your characters with rigs to the library and open them in one scene per file. If you add a bone after animating this will cause shifting as the images being boned will return to their default position relative to the other objects before they were animated.