in-Place Hold eDiscovery Search Failing

I am performing an eDiscovery search on an in place hold with the below PowerShell commands, but is failing with The search you've attempted to run includes too many mailboxes.

Set-MailboxSearch -Identity "inplace hold name" -SourceMailboxes mailenableddistgroupname -SearchQuery subject:'"test test"' -MessageTypes IM -InPlaceHoldEnabled $True -ItemHoldPeriod 90 -TargetMailbox user3@domain.com -EstimateOnly $true -ExcludeDuplicateMessages $false -force

Start-MailboxSearch -Identity "inplace hold name"

The distribution group contains 2043 members.

The account running the search has he required permissions.

Our throttling Policy is below:

ComplianceMaxExpansionDGRecipients    : 10000
ComplianceMaxExpansionNestedDGs       : 25
DiscoveryMaxConcurrency               : 2
DiscoveryMaxMailboxes                 : 5000
DiscoveryMaxKeywords                  : 500
DiscoveryMaxPreviewSearchMailboxes    : 5000
DiscoveryMaxStatsSearchMailboxes      : 100
DiscoveryPreviewSearchResultsPageSize : 200
DiscoveryMaxKeywordsPerPage           : 25
DiscoveryMaxRefinerResults            : 10
DiscoveryMaxSearchQueueDepth          : 32
DiscoverySearchTimeoutPeriod          : 10