I haven't had much luck lately with new equipment (see some of my other posts/rants).
I ordered a new Focusrite ISA One Preamp and it came in late Thursday.  Friday morning I was checking it out.  I used a mic cable with a Neutrik connector that I've been using in my studio for a couple of years to connect a microphone to the ISA One.  Everything checked out and the ISA One is a "keeper" comparing it to other preamps I have.  However, when I tried to remove the mic connector from the ISA One it wouldn't budge.  I pressed on the release button on the XLR jack but the connector wouldn't budge.  Even trying to pull with pliers would not remove the connector.  I finally gave up and just cut the mic cable and left the connector in the jack.  I've RMA'd it and will get a replacement after the vendor gets the defective unit back. 
 
I've worked with XLR connectors and jacks with the latch for many years and never had a problem before.  "Murphy's law strikes again"
 
I will make sure I only use XLR connectors without the latch cut out in them on the replacement unit.

I have to give AMS a plug for handling the replacement.  Most companies will not replace a defective item until the defective item has been returned and then its usually several days before the replacement is sent.
 
I dropped off the defective unit at UPS on Friday.  Yesterday, AMS shipped out the replacement without waiting for the defective return.  ETA is tomorrow (Wednesday) for delivery of the replacement.
 
 

Great.  I love it when companies do right.
 
I've heard of certain cables that have problems, but that must not have been your brand(s).  It was probably one of those "this is off spec just enough" to mismatch with "this out of alignment just a little" other.  I've got a mic that is picky about cables.  Very frustrating.
 
@ 

The cable I used had a Neutrik connector and has been used for several years and plugged into other XLR jacks with the latch and no problem.  Just a defective connector in the ISA One. 
 
 
 
 

I hope they send you another cable, then.  That would make an even happier ending.

I've already put a new Neutrik connector (without the latch cutout) on the cable.  I'm not going to press for a new cable.
 

They only fall out easy when you don't want them to!  I've had that happen before with a jammed XLR and it was the little lever gets bent and doesn't move far enough. You have to get in there with a small screw driver. No fun at all when your in a hurry to break down after a long night.

Got the replacement ISA One, checked it out, using a mic cable connector without the interlock notch, and mounted it on a shelf in my rack.  Connected it with a cable from my XLR Patch Panel without the interlock notch in the connector.  I'm "gun shy" after the problem with the connector in the first unit.