Symfony表单无法保存Many-to-Many关联，手动添加正常

我有一个简单的博客表单，其中blogCategories字段为多对多关联。调用persist前，Blog对象已包含blogCategories数据，但执行flush后，关联表中并未生成对应条目，且无任何报错。不过若手动调用$blog->addBlogCategory($blogCategory)传入BlogCategory对象，就能正常保存，这说明关联配置无误。

手动添加后的对象结构如下：

App\Entity\BlogEntry {#628 ▼
  -id: null
  -name: "65730a3121b23"
  -headline: "test"
  -content: "<p>stack overflow</p>"
  -published: true
  -preview_picture: null
  -releaseTime: DateTimeImmutable @1702038065 {#1255 ▶}
  -blogCategories: Doctrine\Common\Collections\ArrayCollection {#629 ▼
    -elements: array:4 [▼
      0 => App\Entity\BlogCategory {#1269 ▼
        -id: 2
        -name: "1869478cc6"
        -ident: "Betriebsrat"
        -blogEntry: Doctrine\ORM\PersistentCollection {#1276 ▶}
      }
      1 => App\Entity\BlogCategory {#1273 ▼
        -id: 3
        -name: "017623d368"
        -ident: "Gut drauf"
        -blogEntry: Doctrine\ORM\PersistentCollection {#1272 ▶}
      }
      2 => App\Entity\BlogCategory {#1270 ▼
        -id: 4
        -name: "13afe00644"
        -ident: "Heimbeirat"
        -blogEntry: Doctrine\ORM\PersistentCollection {#1294 ▶}
      }
      3 => App\Entity\BlogCategory {#1304 ▼
        -id: 5
        -name: "0635ff2d31"
        -ident: "IT"
        -blogEntry: Doctrine\ORM\PersistentCollection {#1371 ▶}
      }
    ]
  }
  -author: Proxies\__CG__\App\Entity\Employee {#472 ▶}
}

已解决：在表单字段配置中设置by_reference=false即可正常工作（感谢Marleen的提示）。

内容的提问来源于stack exchange，提问作者Pilotzi