[BUG]: Fluent Detail List - Not displaying data in Play mode and throwing errors " , observed "

[Dohsan]

Describe the bug The Fluent Details list no longer displays data in play mode (but does in edit/design studio). This behaviour has been found on all our apps once we have to edit them and the authoring version is automatically updated.

On Error is triggered when entering a screen with the fluent details and displays errors for the fluent details items property and for any labels referencing a property derived from the fluent details (Pagination, page counts etc.).

Error is displayed as " , Observed: .<Prop> Source: " (See screenshot below)

Monitor does not display any additional data of note (see screenshot below)

We have found authoring version 3.24044.28 does not display this issue. We deploy via DevOps pipelines, so for the time being are reverting the authoring version to this, as it is no longer selectable when in the app. However, long term this is not sustainable.

All fluent details lists are setup to use delegable galleries as the source with external paging & sorting

To Reproduce Steps to reproduce the behavior:

1. Set Authoring version to anything past 3.24044.28
2. Enter Play mode
3. Navigate to screen with fluent details

Expected behavior Expectation that the data displays and no errors raised

Screenshots App: Montior: Monitor Details:

[denise-msft]

@Dohsan our team is having trouble reproducing this.

Can you please share the formula that you're using on the Items property of the DetailsList and the Gallery control?