RTC 4.0.4 zOS scm cli using lscm - when normal exit 0 from omvs shell script there is still a hanging STC for OMVSEX which has to be cancelled - why?

I have an omvs shell  script that executes some lscm commands. Some of the commands get errors but when exiting the shell script I  exit with 0 (zero) and I get the usual omvs prompt. When I then enter exit and hit enter a second time to exit omvs nothing happens. I have to press the escape key to get a command prompt and enter "quit" in order to get out of omvs. What do I  need  to  do to exit the shell script - AND - get a "normal" omvs prompt where I can do a "normal" exit to return to tso/ispf? Also each time  I exit the shell script after executing lscm commands I get a "hanging" STC with step name OMVSEX. What do  I need to do  to not have hanging STCs after executing lscm commands?

I get into omvs by ISPF menu option 6 (command) and then enter omvs.