OK, I tried the CPC control of regular portals (the regular portals had no trains programmed). After saving a session, exiting, and returning and resuming a session the CPC portals had the clock reset to zero, and the sequential list of trains back to the first in the list. This is with emit immediately set to "NO". I tried removing all CPC programming and using the standard portals. These don't allow sequential lists and don't have emit immediately. But again, after saving a session, exiting, and resuming the timer is set back to zero and new trains are emitted as if from the initial start time.
I tried this both in TANE and Trainz 2019.
This is disappointing because I was trying to set up some schedules. I guess my alternative is to make large(ish) staging yards and use "Wait Until [clock time]" commands.
It appears the original author of CPC (sforget) is no longer active in Trainzing.