Creation of subpages fails in certain model constellations

[twiro]

I'm currently working on a new website that was running just fine on 5.0.0-beta.3 in the last weeks and the client had no problems entering and structuring their content in the panel.

After the recent update to 5.0.0-beta.4 we face some heavy issues in the panel that makes working on the content nearly impossible right now – the main problem that struck first was that creating new pages failed in most cases and it took me quite some time to understand which cases actually were affected. I tried my best to track it down and this is what seems to happen:

Description

Trying to create a new subpage under the following conditions fails and throws the type of errors listed below:

Conditions:

1. A default page model is used
2. The template of the parent page has its own page model
3. The template of the subpage has no own page model

Errors:

• Kirby\Cms\Page::model(): Return value must be of type ProjectPage, DefaultPage returned
• Kirby\Cms\Page::model(): Return value must be of type ArticlePage, DefaultPage returned
• Kirby\Cms\Page::model(): Return value must be of type ProfilePage, DefaultPage returned

Workaround:

As soon as not alle three conditions are met at the same time, creating subpages works again.

Screenshot

Your setup

Kirby Version: 5.0.0-beta.4

[distantnative]

Can reproduce it and already have an idea where the regression occurred.