Bug? AWS WAF & Shield - WebACL Creation intermittently fails to attach to the specified resource

I guess this is more of a Bug Report in the AWS Console than an actual question... but here goes.

I'm not sure if it's getting in a strange state, or if there's a race condition, or what, but when we recently created a new WebACL and attached it to our ALB, in both our production and test environments, the attachment never completed, despite going through the full wizard.

I ran some ad-hoc tests and my only thought is that maybe the browser is orchestrating the calls, and maybe a backend pipe is getting disrupted at some point and so AWS just silently fails to attach the ALB to the WebACL. There also might be something involving navigating between the section pages a few times that might also be disrupting the state in some way, but I was able to get a good number of inconsistent repros.