Hydration doesn't work for ng-templates that are defined inside of another component

[skoropadas]

Which @angular/* package(s) are the source of the bug?

Don't known / other

Is this a regression?

No

Description

Hydration doesn't work on ng-templates declared inside another component's tag, it feels like ng-content hydration somehow affects this.

For example, in this scenario, app-comp2 won't be hydrated:

<app-comp1 [content]="content">
  <ng-template #content>
    <app-comp2></app-comp2>
  </ng-template>
</app-comp1>

But it will in this case:

<app-comp1 [content]="content"></app-comp1>
<ng-template #content>
  <app-comp2></app-comp2>
</ng-template>

Please provide a link to a minimal reproduction of the bug

No response

Please provide the exception or error you saw

No response

Please provide the environment you discovered this bug in (run ng version)

Angular CLI: 17.3.6
Node: 20.11.1
Package Manager: npm 10.2.4
OS: darwin arm64

Angular: 17.3.7
... animations, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, platform-server
... router

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1703.6
@angular-devkit/build-angular   17.3.6
@angular-devkit/core            17.3.6
@angular-devkit/schematics      17.3.6
@angular/cli                    17.3.6
@angular/ssr                    17.3.6
@schematics/angular             17.3.6
rxjs                            7.8.1
typescript                      5.4.5
zone.js                         0.14.5

Anything else?

No response