Hello,
I also experienced this problem

Main theme would sit on 88% – all the other Demos would freeze on 80% (wasted hrs waiting)
All content had loaded except Demo Content. Tried a few different configs with selecting what would be installed. None worked.

Altho it is a fresh install of Wp, I had added an img, site identity and modified Hello Word. I used WP reset (as advised within setup) and tried again – success ! (but the install was exceedingly slow)

Jamison64