You changed your standard point size for leaders with text (MLeaders), and you're unable to update your old leaders.
1. Select one of the MLeaders with text that aren't updating.
2. Right-click the selected MLeader. Then select the Select Similar option from the menu that opens.
3. Change the Mleader style to Standard. The MLeaders should now look tiny.
4. Type PRG in the Command line and press Enter to purge all Land F/X MLeader styles from your drawing.
5. Place a new MLeader off to the side.
6. Change the old MLeaders to the new style that populates. They should now change to the correct size.
You can use the Select Similar option again to select and change all the old MLeaders.
7. Delete the MLeader you placed off to the side in Step 5.