I have a template I use for meeting minutes.
It has several tables for the Agenda items and Actions etc. Because I copy and paste it into Word or Outlook for distribution, I use another table 1 row deep by 1 column (in blue), to create a divider.
AMN_Table1.jpg I find that if I select the last row of a table - say for the Agenda (e.g. select row with item 5). And insert rows. As a row is added below the row selected, the 1r x 1c table is also being expanded... You cannot remove the expansion, but have to delete it, and recreate.
AMN_Table2.jpg If i insert in any row other than the last one, all is ok.