Advice on heat transfer with fluid-structure interaction

I've been having trouble getting a certain problem to work properly. I'm trying to simulate heat transfer from a moving solid to a fluid, where the solid excites the fluid. The test file I created (attached) is a steel sphere in an air chamber. The sphere induces motion in the air, and the sphere is also a heat source.

If I only take into account the Fluid-Structure Interaction interface (Study 1) I have no trouble getting the solution to converge. But adding in heat transfer/flow/multiphysics (Study 2) doesn't work.

Using the Fully Coupled solver works on Study 1 but not on Study 2. I was able to get a Segregated solver to work on Study 1, but again, not on Study 2.

I'm pretty certain that the issue is either that I'm not putting the interfaces together properly, or that I just don't really understand the solvers. I'm still learning COMSOL and I've scoured the documentation looking for a good summary of what each solver does and when it should be used, but I haven't really found anything that explains it. The examples, unfortunately, are no help because all they do is tell you to use X solver with Y settings without explaining why.

Any help would be appreciated here, at least to get me on the right track. And if there's any good (practical) documentation on the solvers I'd also be interested.