Vue transition-group not working with slots?

[gmanish]

Version

2.6.7

Reproduction link

https://jsfiddle.net/gmanish/L3y8j57s/

Steps to reproduce

See that there's a within an opening/closing transition-group tags in the tabs component template.
Click on the tab headers to switch between tabs.

What is expected?

Expected to see the transition between tabs happening with the specified transition out-left.

What is actually happening?

While the tab contents switch as expected, the transition-group seems to have no effect. The transitions are not rendered.

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Similar flattened code, i.e. without the components and slots, works just fine.
I ran into this issue while trying to create a carousel slide component with transitions left-out/right-out transitions depending on whether we're moving to the next/previous slide.

[posva]

transition-group are for lists of elements but you are displaying only one at a time. I imagine you saw a warning on the console upon initial render telling you to switch to transition-group and that's what you changed it to it but your use case needs a transition component as only one view is visible at a time.
The approach you are using is very hacky, relying on the $children is very fragile. Here is another approach using named slots: https://jsfiddle.net/er45s0ag/ (you can use transition-group too), you can automate more things like setting the key if you use render functions and have selected state in tab using inject/provide

Your issue reminded me of #5661 (comment) btw

[gmanish]

You are right, I started using transition-group when I got the console warning for my use case.

The referenced comment above, seems to indicate that transition-group doesn't work with v-show. However, I have a working example here:
https://codesandbox.io/s/lp4yo72q39?fontsize=14

The structure is essentially the same, except there are no components and slots. This works just fine.

Btw, the $shildren logic was picked up from laracasts.com, which I thought was a reliable place to learn Vue through screencasts.