UR12 + Logic Pro X + MacBook Pro 2017 Recording issue

Hi everyone, I have a problem here and hope someone can help me…

Now I am using the Macbook Pro 2017 with the latest iOS (CPU 2.9 GHz, DRAM 8GB DDR3)
Logic Pro X version : 10.4.0
DAW : UR12 Firmware 1.9.10

Now I am having a problem…
When I have done the MIDI recording and tried to record my vocal via UR12.
Sometimes the Logic Pro playback will intermittent, and the playback time bar will jump back for less than 1 second and keep playing.
This will keep happening when I connect the UR12 to the computer and set the inout/output device as UR12.
But once I unplug the UR12 (Or change the I/O device back to system built-in) the problem will be solved.
And I will try again to connect the UR12. and the intermittent issue comes back…
Oh by the way, I have also tried to lower the buffer size into 128 and even 256, still it’s not okay…
Could that be the USB2.0 from UR12 but the thunderbolt 3 (USB-C) from MAC can support 3.1?
If yes…what can I do? When it happens, I cannot record at all.

Another issue is that I am using a 3.5mm jack headset for UR12 direct monitor.
So I am using a convertor to connect to my 3.5mm jack and plug into the direct monitor input.
For what’s strange is…I will hear the sound of electricity popping in my headset…
Is this the problem of the convertor jack? or…the UR12 itself?

Please someone help me…
I’ve been bothered by this problem for a long time and I even bought another interface from other brand…
But still I like the quality of Steinberg…So really wanna get this thing done…

Thanks!!