Searching Lync Centralized Logging Using Time

This is my first attempt to use the Centralized Logging Service to try to generate some logs for a problem a user is having, so perhaps I'm not doing something right. I'm using the commands below to start, stop and search the CLS, but every time I include a StartTime in the Search-CsClsLogging command it returns nothing.

This is the command I'm running to start the logging: Start-CsClsLogging -Pools 'pool01.domain.com','pool02.domain.com','edgepool01.domain.com','edgepool02.domain.com' -Scenario IncomingAndOutgoingCall -Duration 0.00:15

This is the command I'm running to stop the logging: Stop-CsClsLogging -Pools 'pool01.domain.com','pool02.domain.com','edgepool01.domain.com','edgepool02.domain.com' -Scenario IncomingAndOutgoingCall

This is the command I'm running to search the logging: Search-CsClsLogging -StartTime '7/20/2016 14:08:50' -EndTime '7/20/2016 14:12:51' -LogLevel All -OutputFilePath 'C:\logfile.txt'

I run the commands in that order Start, Stop, Search. When I include the StartTime parameter I always get no results returned. The documentation says the time should be in local time, which it is, but I've also tried using UTC and that doesn't work either. If I don't include the StartTime I get the log file written to.

Am I running these command incorrectly? I cannot see why including the time continually yields a blank output file.