Unity 2021.1.7f1, TMP 3.0.6 Should be reproable in other Unity versions too Repro: 1. Add a TMP Input Field to a scene 2. Move it under a parent object that has a HorizontalLayoutGroup 3. Enable only the "Control Child Size: Width" option 4. Edit the text in the input field What I expect: The width of the input field rect transform increases to match the preferred width driven by the parent layout group What happened: The width stays the same and only updates if the parent layout group is updated by e.g. deactivating and activating it I investigated the source code of TMP_InputField and found the cause to be a failure to call LayoutRebuilder.MarkLayoutForRebuild in Scripts\Runtime\TMP_InputField.cs:3253 if the game object does not have a ILayoutController component attached. In reality the parent controller should also be taken into account. m_IsDrivenByLayoutComponents seems like an unnecessary optimization that causes this bug as MarkLayoutForRebuild is already optimized internally.