When playing with a listen server and 1 client, if an asset window is not open, the client exhibits unusual behavior

I know this is going to sound extremely strange, and I can provide a video if necessary, but here’s the problem:

-If I play with a listen server and any number of clients > 1, everything replicates properly and there are no issues.

-If I play with a listen server and only 1 client, but have any asset window open while playing (be it a BP, mesh, animation, etc.), then there are no issues.

-However, if I play with a listen server and only 1 client, but do NOT have any other windows open, the client begins to lag (on their screen and server’s screen) and exhibit unusual behavior, but only if I perform actions that involve replication of movement. Mind you, as I said, the replication code isn’t broken, because once I open an asset window or play with multiple clients everything returns to normal.

I’ve tried: restarting my computer; migrating to a new project; creating a fresh Animation BP and copying everything over; deleting everything in the project except the content folder; removing all code running on tick.

I understand I could simply do my testing with an asset window open, but I’m concerned this issue could point to a deeper problem that is going to come back to bite me later, and I’d also feel much better if this wasn’t a problem. Really hope someone can makes heads or tails of this…