One other thing...I can say this with a straight face because I have done it...on purpose, of course.
 
Make sure you are singing into the correct side of the mic. I know -sounds silly - But the AT3035 looks pretty much the same forward and back. The side to sing into is the one with the big black lettering :"audio-technica". If you reverse the mic - depending on your studio treatments - The difference in sound may not be immediately obvious. Your vocals will sound muddier and more distant, as I recall. 

One answer- BUSS POWER-- I think it is a bad way of making an interface. At least have the option of using a power supply. I always advise against purchasing interfaces that only use buss power. Had a friend who had weird issues like yours and he traded up to the 6i6 and they all went away. 
Phantom power needs a lot more current than a whimpy usb can supply,,, it's like having dead batteries. 

Yes, that sounds like something I would do.    But I am singing into the correct side.   
 
Thanks!
Greg

Cactus Music
One answer- BUSS POWER-- I think it is a bad way of making an interface. At least have the option of using a power supply. I always advise against purchasing interfaces that only use buss power. Had a friend who had weird issues like yours and he traded up to the 6i6 and they all went away. 
Phantom power needs a lot more current than a whimpy usb can supply,,, it's like having dead batteries. 

Everything was working fire until recently.  So it could be that my USB port is now bad.   But at one time it all worked.    
 
Hmmm.... interesting.   I will look into the 6i6.
 
Thanks for the input!
Greg

I was just looking at the 6i6 and came across this video.    See the distance of the guy singing from the mic.   When I record with the Gain at 2 o'clock, I'm about 4-5 inches away if I'm singing loud.    Otherwise, I'm right up on the mic, about 2 inches +/-
 
However, I also noticed that the Gain with the green chord for the Fender Rhodes is at 4:00, and the black chord for the mic is maxed out. 
 
https://www.youtube.com/watch?v=Zd_PC7KMtjA

I have an AT 2020, I would think they are very close in operation.  With my 6i6 the gain is around 12 o'clock and that can still peak out.  I stay about 5" from the mike.  
If you turn my pre amp gain up past 2 o clock using the mic input setting you'll start to hear a lot of background noise. With nothing plugged in. 
Something is not right if a mike pre amp has to be up that far. I've used a lot of different pre amps in my day and 2 o clock is almost always about right for a SM 58 and a bit less for condensor mikes but not much less.  
I no longer use the 6i6 pre amps for mikes. I found them to unforgiving of peaks. 
I bought a Joe Meek 3 Q which has worked very well for me, It is patched to my line level inputs so by passes the pre amp of the 6i6. 
I still use those for DI of acoustic guitars and miking my guitar amp. The output of a guitar amp is more even in level so it's not an issue. 

Cactus Music
I have an AT 2020, I would think they are very close in operation.  With my 6i6 the gain is around 12 o'clock and that can still peak out.  I stay about 5" from the mike.  
If you turn my pre amp gain up past 2 o clock using the mic input setting you'll start to hear a lot of background noise. With nothing plugged in. 
Something is not right if a mike pre amp has to be up that far. I've used a lot of different pre amps in my day and 2 o clock is almost always about right for a SM 58 and a bit less for condensor mikes but not much less.  
I no longer use the 6i6 pre amps for mikes. I found them to unforgiving of peaks. 
I bought a Joe Meek 3 Q which has worked very well for me, It is patched to my line level inputs so by passes the pre amp of the 6i6. 
I still use those for DI of acoustic guitars and miking my guitar amp. The output of a guitar amp is more even in level so it's not an issue. 

Yeah, turning the Gain up past 3:00 isn't good.   Too noisy.   But there's no way I can record vocals at 12:00.   The signal is just too weak.
 
The Joe Meek 3Q looks great, but I don't know if getting one the way my 2i4 currently is will benefit me.   I'll probably just look into getting a 6i6.
 
Thanks!
Greg

The 6i6 is the best bang for the buck in simple interfaces. It also comes with the Mix Control software which the 2i2 and 2i4 do not have. I really like the 2 headphones systems when working with a few people in the room.  So it's a lot more going on. You can probably sell your 2i4 and get a good price for it. Some music stores would take it on trade up. 

Cactus Music
The 6i6 is the best bang for the buck in simple interfaces. It also comes with the Mix Control software which the 2i2 and 2i4 do not have. I really like the 2 headphones systems when working with a few people in the room.  So it's a lot more going on. You can probably sell your 2i4 and get a good price for it. Some music stores would take it on trade up. 

Normally I would sell something I'm not using anymore.  But since something isn't right about the 2i4, I don't know if it would sell.   I may try it and just be honest about it.   Maybe someone would want it anyway.
 
Thanks!
Greg

So I thought I would try recording vocals using Input 1  (I always use Input 2).   I put the Gain at noon and recorded.  I was getting the same level as I was getting on Input 2 at 2-3 o'clock.   So Input 2 has issues.  
 
However, I also noticed that with Input 2 I can turn the Direct Monitor counterclockwise, and have the vocals stand out.   But it doesn't work with Input 1.  When I turn the knob left, the music is lower, but the vocals don't stand out at all.    So my interface is bad.
 
I will look into the 6i6.    :)
 
Thanks, everyone!
Greg