Checkout from RTC doesnt happen if the Build ToolKit to be used is specified in the form of an environment variable. This is so that the Build ToolKit on slave machine is used.
configurations on Jenkins:
System configuration:RTC build toolkit installation path provided as the environment variable
Job configuration: Override global RTC repository connection option selected for RTC scm.
Overriding the toolkit path in slave configuration using environment variables just lead to Jenkins searching for the toolkit in directory where the slave is located(in Screenshot)
The variations in the way the path was provided: $RTC_BUILD_HOME , %RTC_BUILD_HOME%
The way around this was to hard code path to toolkit in job configuration in which case the slave machine's toolkit was could is not the one being used.