Cannot assign attributes to <router-view> when using <transition> and <keep-alive>

[dneuschaefer-rube]

Version

4.0.1

Reproduction link

https://codesandbox.io/s/inspiring-carson-bjbmm

Steps to reproduce

I ran into an issue with <router-view> not rendering any content, and narrowed it down to a combination of 3 factors:

• using <transition>
• using <keep-alive>
• assigning an attribute to <router-view>, e.g. "class" or "style"

What is expected?

<router-view> renders content

What is actually happening?

When combining all of these, <router-view> renders the content initially, but renders nothing anymore after navigation. It works fine when doing at most 2 of the things mentioned above.