While I see your point I think I probably phrased that badly. This glitch does not happen if I try immediately after an update has occurred. You could wait a long while, then try doing this for the first time manually and it has the potential to happen. However, I wasn't sure if this was an intentional thing where it tries to save processing time from unnecessary tries. As for waiting for avast to load, all the times I have reproduced this avast was not in the process of updating or loading anything heavily (this is not something I suddenly try to interrupt and manually do in the middle of booting in or when it's updating). Furthermore even if this was the case, my computer's more than capable of loading avast's processes/updates quickly after an update so I'm a bit doubtful that there's a correlation here.
I guess to clarify, reproducing the issue is usually by doing a manual program update for the first time since you booted in or since you've updated the definitions. Once this passes, doing manual updates again afterward will not produce this effect (so it isn't a timing thing, more like a first use glitch).