Swiss meringue disaster

 So I have made Swiss meringue buttercream multiple times with no problems. All of a sudden every time I make it my marine get super thick and glossy and when I add my butter it never gets soupy and never really turns into a buttercream. What am I doing wrong? I'm using room temperature butter switching to the paddle and putting it on low when I add the butter

The one and only time I've made Swiss meringue buttercream, I had to mix it for over an hour, but it did finally come together and was good.  I know I did something wrong, but I do not have the patience to fool with a frosting that takes that long to make.  Maybe you just need to let the mixer do its job???

I am not sure why it is not becoming a buttercream. I never have mine go through that curdled stage as I have figured out the perfect temperature/softness for the butter.

I heat my whites/sugar, tip it into a bow, whisk my whites until stiff then switch to my beater blades and add my super soft butter all at once and beat on slow until combined then med-high for a few minutes and it's done.

What do you mean by it never turns into a buttercream?

I've tried Swiss Meringue Buttercream once and it was definitely intimidating but once it was done, it was amazing!! To my understanding, the butter should be added slowly, not all at once.  Even though this has worked for you in the past, perhaps you could try adding the butter one-two pieces at a time.  Hope it works out for you. 

Sounds like a temperature problem too me.  Either the meringue is too warm or the butter is too soft.  I make IMBC but it's nearly the same thing.  I crank up the mixer and rub a bag of frozen vegetables around the outside of the mixing bowl to get it to come together if it looks too soupy.