I hit submit bugs and it sent me here. Sorry if it's the wrong spot.
Downloading Solus Plasma from testing, then installing gives you a situation where, if you select all categories to upgrade, you have 575 packages to upgrade. Once they are all upgraded, software Center is telling you to please wait - that it's installing updates even though updates have finished. If you leave it sitting for 30 minutes, you still see that same screen.
I've repeated this process 3 times: once in a VM and twice on bare hardware (to a desktop and a laptop). In all three instances, the same thing happened. If you reboot to load the updated kernel and go back to software Center, it says that it is fully updated.