Can't update branch from main file

Hi, I have a library file branch that is having trouble updating from the main branch. Whenever I am prompted to update from main file and I attempt to do so the update window shows on the screen and attempts to load but will eventually close itself (while a “Loading” indicator appears behind it in the file).

The only thing I can think is that my library file is too large to easily perform an update from main. The visual comparison never fully loads inside the update window.