OFFICIAL Uno R3 and powered USB hub

I have an official Uno R3 with the basic “blink” sketch loaded and no shields attached- basically clean out of the box. It’s connected to the PC through a 4-port powered USB 2.0 hub. When the PC goes to ‘sleep’, everything is fine, Uno keeps running, drawing power from the hub, but when the PC wakes up, the Uno hangs and has to be reset.
Also, if I disconnect the hub from the PC, but keep the hub powered up for the Uno to get power from, then later reconnect the hub to the PC, the Uno hangs and requires a reset.

Is this expected behavior? And if so, should I expect this behavior also if the Uno is powered by a battery and then later connected to the PC while running?

I have a few projects in mind and this behavior would be unacceptable.

What happens when you plug into toPC directly in the same circumstances?

Weedpharma

weedpharma:
What happens when you plug into toPC directly in the same circumstances?

Weedpharma

Just tried putting the Uno direct to a USB port on the PC and when the PC 'slept' the Uno halted, as would be expected due to power on USB being turned off, but when the PC woke up the Uno just sat there; the 'blink' sketch didn't start.

I'm guessing the Arduino serial port may be thinking a download is about to start and waiting for it to start.

Weedpharma

So, that would suggest something wrong with the bootloader?

That is beyond my knowledge level.

But unlikely to be so on a new board.

Weedpharma

So, no one can confirm this is normal behavior?