
There are a few possibilities that could be causing your SPFx app to disappear in the new version of the MS Teams client on a specific tenant:
Tenant-specific settings: There might be some settings specific to the tenant that are causing the app to not appear in the new version of the Teams client. Check the settings in the Teams admin center for that specific tenant.
App Catalog settings: Ensure that when you uploaded your app to the SharePoint App Catalog, you enabled the option "Make this solution available to all sites in the organization". This setting is crucial for the app to be available across all sites in the tenant.
App visibility: Ensure that your app is not hidden in the Teams client. In the Teams client, go to the "Apps" menu, select "Manage your apps" and check if your app is listed there.
App update: If you've recently updated your app, there might be a delay in the propagation of the update across all tenants. Wait for some time and check again.
Cache issue: Sometimes, clearing the cache of the Teams client can resolve such issues. Try clearing the cache and then check if the app appears.
Thanks,
Prasad Das
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