This can happen a couple different ways.
league rules were not configured to use split season
Go to Setup >League > Split Season tab of the league rules and click and indicate that the league will be bowling in more than one parts.
Indicate the number of parts (splits) and the week numbers that the splits BEGIN in the Split Season Schedule rules.
Indicate that the team points are reset at the start of the new split.
·The wrong week number was configured for when the split begins.
Go to Setup >League > Rules > Split Season tab of the rules.
Ensure that the week numbers indicate the weeks that the splits BEGIN and not END.
·You are using a report style for Team Standings that shows Year to Date Wins and losses, not current Wins and Losses for the split.