TYPO3 Core

I'm currently doubting myself as I believe I found an unbelievable bug in fluid_styled_content (please dont't get me wrong here - I don't mean to be condescending or anything and I admire the work of the Typo3 community, I just can't believe this potential bug obviously hasn't popped up anywhere else yet).

I found that when adding fluid_styled_content to any section not named "Main", nothing will be rendered. Furthermore, if a section is named "Main" and fluid_styled_content is added to that section, all other sections will not be rendered.

I put up a fresh VM to verify this and currently have two installations that show this problem. I did not dig into the code yet - if I find anything, I will add it here.

Here's how to reproduce:
- Install current Typo 8.7.8 (don't import anything, just a basic installation - this also happened to me in 8.7.6)
- create a single page
- add a template for a new site
- include fluid_styled_content within the template

Add this typoscript:

config {
    doctype = html5
    language = de
    locale_all = de_DE

    renderCharset = utf-8
    metaCharset = utf-8
}

styles.content.get = CONTENT
styles.content.get {
    table = tt_content
    select.orderBy = sorting
    select.where = colPos=0
}

### normales Template
page = PAGE
page {

    10 = FLUIDTEMPLATE
    10 {
        templateRootPath = fileadmin/Resources/Private/Templates/
        partialRootPath = fileadmin/Resources/Private/Partials/
        layoutRootPath = fileadmin/Resources/Private/Layouts/

        file = fileadmin/Resources/Private/Templates/Index.html

        variables {
            content_main < styles.content.get
        }
    }
}

Create a Default.html layout file with the following content:

<f:render section="Main" />

<f:render section="Other" />

Then, create an Index.html template file with the following content:

<f:layout name="Default" />

<f:section name="Main">
    <h1>This is section "Main"</h1>
    <f:format.raw>{content_main}</f:format.raw>
    <p>This is the end of section "Main"</p>
</f:section>

<f:section name="Other">
    just some more content
</f:section>

As long as you don't add anything, all sections will be rendered correctly. Same applies if you add custom elements.

But as soon as you add a fluid_style_content element, only the "Main" section will be rendered.
If you try to rename the "Main" section to anything else, nothing will be rendered at all. As soon as you remove / disable the content element, everything will be fine.

I don't see what could be wrong with this simple setup, so I'm assuming that it must be a bug...

Kind regards,
Christian