I'm not sure how much hot coffee creamer I put in the buttercream. I make a version of it all the time (using all Crisco sticks) and it turns out fine. I think I added too much creamer this time, turned on the mixer and let it run. When I came back to it, my buttercream was kinda "soupy". It's been in the refrigerator for a few days, and I am hoping I can re-whip it and get better results. What do you think?
The humidity might have contributed to your problem. You should be able to add more powdered sugar and bring it the consistency that you want.
It has been very humid. The buttercream is already so sweet, I hate to add more sugar, but I will try and re-whip it. Maybe add some Dream Whip