CollectionView GroupHeaders do not resize if you hide the content

[Axemasta]

Description

This is a very similar issue to #28012 which that has been fixed for CollectionView.Header, the same issue occurs when trying to hide the content of a GroupHeaderTemplate.

When using a CollectionView with groups, once the cells have been rendered if you set the GroupHeaderTemplates root view visibility:IsVisible="False, the header cell's content dissapears but its height is not recalculated, leaving an empty space where the header content was.

This also affects height requests, once the cell has been rendered if you set a new HeightRequest, the cell's height will remain at whatever height it was rendered at.

I have supplied a fully coded reproduction, below are screenshots from this sample app of both how this actually behaves vs how I expect this to behave.

Group Headers Visible	Group Headers Hidden (Expectation)	Group Headers Hidden (Reality)

Steps to Reproduce

• Create a grouped collection view
• Add a grouped header for the collection view
• Add a mechanism to toggle the visibility of the grouped header (ie a switch & binding x:Reference)
• Run the app
• Toggle the visibility of the header from true to false

Expectation:
The header cell content dissapears and the group header cell resizes, hiding the group header completely

Actual:
The header cell content dissapears but the cell remains the same height, leaving empty space where the group header was

Link to public reproduction project repository

https://github.com/Axemasta/MauiRepros/tree/main/src/GroupHeaderResizingRepro

Version with bug

9.0.90 SR9

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

iOS, Android

Affected platform versions

Any

Did you find any workaround?

I have attempted to use triggers to set the HeightRequest to 0, however this only works when new group headers are rendered, it does not affect group headers which are currently being displayed therefore not much of a workaround.

Relevant log output

[similar-issues-ai]

We've found some similar issues:

• The header in a collectionview does not resize if you hide the content #28012 , similarity score: 82%

If any of the above are duplicates, please consider closing this issue out and adding additional context in the original issue.

Note: You can give me feedback by 👍 or 👎 this comment.

[SuthiYuvaraj]

This issue has been verified in Visual Studio Code 1.101.0 with MAUI versions (9.0.0 & 9.0.90). It can be reproduced on the Android, iOS and Windows platforms.

[Axemasta]

Tested against Maui 10.0.90 and this is still an issue.

Alot of work has gone into CollectionView but this is definitely something I'd come across in my app where the first group is always hidden. My app is still using Sharpnado for the most mission critical list, and this is the final hurdle in my way to be able to swap to maui. I sound like a broken clock but CollectionView would be best served by creating a torture suite of real world use cases (such as this) and writing a ton of tests to ensure it behaves as expected in every scenario!

[kubaflo]

Thanks for confirming the current CollectionView behavior. The revalidation label is no longer present, and the issue will remain open for investigation.

Disclosure: this comment was generated by AI.