So after going through all the usual suspects, I discovered that with the current patch the "No Running on Residential Lots" mod causes two issues, so you probably want to avoid it for the time being.
1. If you invited Sims to current lot, you will get the message "XXXX will be right over!", but they never show up.
2. For you children/teen sims, if you invite a classmate over after school, they will not show up either.
I would say avoid this one for the time being.