In some environments, a Delivery Group may contain a mixture of VDAs from different Catalogs, with each set containing their own specific set of applications.  These VDAs may have Tags, with the relevant applications limited to VDAs with the specified Tag.  Attempting to modify one of these tag-limited applications may result in a failure.

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Under the current design, Studio expects any hosted applications to be installed on all VDAs in a Delivery Group.  As such, when selecting a VDA to use for processing changes to any application, the default behavior of Studio is to select the lowest numbered VDA that is online and Registered.  Tags are not processed during this selection, which can result in the selection of a VDA that does not have the application installed.  In this instance, attempts to modify the application will fail as Studio cannot confirm these settings against the selected VDA.

Two workarounds exist for this issue.

1. Prior to attempting to modify the application, power off all VDAs in the Delivery Group that do not have the application installed.
2. RDP/Console into a VDA hosting the targeted application, then install and use the Remote PowerShell SDK to modify the application.
   1. Remote PowerShell SDK does not require a reboot to function, and installation on any Non-Persistent VDA will be removed at next reboot.
   2. Examples for File Type Association:

      1. Get-BrokerApplication -Name "Adobe Acrobat" | Set-BrokerApplication -FileTypesEnabled $true

      2. $app = Get-BrokerApplication -Name "Adobe Acrobat"
         
         Set-BrokerApplication -InputObject $app -AssociatedFileTypeName @(".pdf", ".pdx")

A Delivery Group with a mix of VDAs, where only a subset of those VDAs contain a specific application, can result in a failure to modify that application.