Yes, I have had no issues connecting multiple USB devices using USB hubs, but only if the hub only has USB ports. If it has other features like HDMI or SD card reader then I can't get it to work.
Yes, I managed to fix this.
The issue is that the code is getting stuck in the while loop in the write_packed function.
Here is my fix:
I added a condition so the code can exit the loop
Then I determined that the issue was due to the SysEx...