I've used the same recipe dozens of times and never a problem. Now my first huge wedding cake and the buttercream sticks to my viva towel.
I have already frosted all 5 layers, is there anything I can do?
Help! Maybe if I just leave it out overnight and try in the morning?
A few of the small tiers might fit in the fridge, would that help?
HELP!

I would try the 'frig trick .... I put mine in the 'frig sometimes after I crumb coat to get it to set a little faster.

What if I put a new batch of buttercream over top the sticky buttercream?
Would that maybe work, I'm getting very stressed with this.

I would fridge it and if it is still not crusting, I would hot spatula it. Not as good a result as Viva, but it will smooth out the biggest ripples. What kind of other decor is on the cake? Anything that will draw the eye away from the imperfections??

Yes, the fridge and hot knife is helping. Thank you very much! It's looking better, what usually takes 30 minutes has taken me many hours.
Thanks again for the help.