Time Machine hanging after deleting big files

A couple hours ago I deleted upwards of 70GB of files from my HD by cleaning out some huge Final Cut Pro libraries from completed projects. I was down to 28GB on my 1TB SSD drive and now the Finder window tells me that I have over 105GB free. I'm trying to make a new backup in Time Machine but on repeated attempts, TM stalls/gets stuck and goes no further. Currently it's been stuck at "Backing up 383.3 MB of 9.86 GB." Any guesses as to what's happening?

Thank you...