A couple weeks ago I installed the initial release of Catalina on three Macs, seemingly without any problems. Then when I was prompted to install the 10.15.1 update on one of them (iMac Retina 4K, 21.5-inch, 2017 w/Radeon Pro 560 4 GB), I proceeded with the installation – and since they have been plagued by constant crashes (seemingly when it goes to sleep) and then crashes while booting (usually at the white bar is two-thirds of the way across). I've reinstall the OS multiple times, eliminated any trace of 32 bit software, uninstalled almost all non-native software, disabled all items at start-up, etc. Below is the most recent crash report.
Any ideas on what else to try? Also, is there a way to find the relevant boot logs to see what's causing the crashes at boot up?
System Crash Report