Shinyapps.io SQL problem

HI, I am experiencing a 'hang' when executing SQL select with an 'inner join' against a remote MS SQL Server database when deploying application on shinyapps.io. No error message in log. Works locally so I presume it is a driver-related issue. I am using DBI ODBC and dbGetQuery using a pool connection.
Has anyone had same/similar experience.
Many thanks.