Bad Gateway 502 when using "Find Documents by saved search"

Question

Hi, 
 My flow using "Find Documents by saved search" appears to be failing - Bad Gateway 502 Error. It works fine when search is configured for extreamely narrow range of documents, however it appears to fail every time saved search range exceeds a few hundered document matching items. 
 Any advice? 
 
 { 
 "inputs" : { 
 "host" : { 
 "connectionName" : "shared_bentley" , 
 "operationId" : "FindDocumentsBySavedSearch_V2" , 
 "apiId" : "/providers/Microsoft.PowerApps/apis/shared_bentley" 
 }, 
 "parameters" : { 
 "connection" : "projectId=e3f7388f-5b16-4382-a7b1-67b8398b51fa&dataSource=Bentley.PW--arcadis-uk-pw.bentley.com~3AArcadis-UK-07&workAreaId=7672f74c-6d6c-4972-9396-16dce2e4867c" , 
 "savedSearchPathOrId" : "./Saved Searches/Global/07 - All Files" , 
 "environment" : "DJV_Documents" 
 }, 
 "authentication" : "@parameters('$authentication')" 
 }, 
 "metadata" : { 
 "projectId=e3f7388f-5b16-4382-a7b1-67b8398b51fa&dataSource=Bentley.PW--arcadis-uk-pw.bentley.com~3AArcadis-UK-07&workAreaId=7672f74c-6d6c-4972-9396-16dce2e4867c" : "1MC06 - Phase 2 - 1MC06 - 1MC06" 
 } 
 } 
 
 OUTPUTS: 
 
 {"statusCode":502,"headers":{"Request-Context":"appId=cid-v1:b708ff59-448d-483f-b1e1-063ddb7fe47e","Strict-Transport-Security":"max-age=31536000","x-correlation-id":"ab6bdfac-17dc-409a-b343-6db163092971","Set-Cookie":"ARRAffinity=45df15217c96d521581cb385bb0e2b0a144929ebf3171b452a3e468370a3cde3;Path=/;HttpOnly;Secure;Domain=connect-projectwiseflow.bentley.com,ARRAffinitySameSite=45df15217c96d521581cb385bb0e2b0a144929ebf3171b452a3e468370a3cde3;Path=/;HttpOnly;SameSite=None;Secure;Domain=connect-projectwiseflow.bentley.com","X-Powered-By":"ASP.NET","Timing-Allow-Origin":"*","x-ms-apihub-cached-response":"true","Date":"Wed, 14 Oct 2020 13:55:38 GMT","Content-Length":"332","Content-Type":"application/json"},"body":{"error":{"code":502,"source":"flow-apim-msmanaged-na-eastus2-01.azure-apim.net","clientRequestId":"ab6bdfac-17dc-409a-b343-6db163092971","message":"BadGateway","innerError":{"statusCode":502,"error":{"message":"An unknown error occurred."}}}}}