Can anyone help... This is my third batch of IMBC, the first 2 were great.... This new batch took a long time to come together, chunky at first.... then after an extra 10 min... Was just ok, not as smooth as the other batches I've made. What going on.... Any suggestions...

It's now summer, dear lady.

Put a quarter of your batch in the fridge for a half hour. Let the rest sit on the counter. Then beat the cool part into the room temperature part.

Bakingirene.... Will this separate at all when remixed... I have a cake to do tomorrow and don't have time to remake ???

If it is at the right temperature it will NOT separate.

If it's separating then it's too warm or too cool.

No need to discard. Just make sure it's at 20-22C tomorrow before you start remixing it. Here to reassure you is expert advice http://www.kingarthurflour.com/blog/2011/01/04/the-beautiful-side-of-baking-blissful-buttercream/