Yes, I had never used a source-built engine version before. Following your advice, I replaced both the Character and PlayerController, and finally discovered that the issue was with my PlayerController Blueprint. I subclassed the same base class to create a new PlayerController Blueprint and replaced the old one—and everything started working. I used Diff Selected to compare them and noticed the old Blueprint had “Replicate Using Registered Sub Object List” checked—however, even when both Blueprints had exactly the same settings, the old one still failed while the new one worked. It’s weird, but in any case, that fix did resolve the issue for me. Much appreciated!