When trying to access the production version of Endevor (in this case v17) in TSO and then trying to access the test version (in this case v18.1). The attempt to access v18.1 fails.
This worked for us under v16 and v17.
A change was made in v18.0 to not allow the swap of Endevor versions without logging off and logging on again.
This would automatically be done if the use of the supported method of a Concurrent Releases (see "Concurrent Release Considerations" in the documentation under Installing then Preparing For Installation).
This method is to use a different TSO logon proc for each release. If this method is used, the production version could use either Steplib or Linklist and the Test version would use Steplib. This enforces the logging off and logging back on to change the TSO logon proc.
In this case the Dynamic Steplib was used to re-allocate the Steplib. This is not a supported method. It does work except it requires a logoff and logon each time the swap of versions is needed.
Release : 18.0 and later
Component : CA Endevor Software Change Manager
log off and log on each time if there is a need to swap versions.