Having just installed MLO2 on my iPhone and sync'd with my Windows desktop and I am not seeing all Active Actions in the To-Do list on the iPhone.
Only a small number of Active Actions are displayed on the iPhone. 16 in total compared to the 67 shown on the Windows version. All the tasks are shown correctly in both versions, just most Active Actions are missing on the iPhone version. However all Due Actions are correctly shown on the iPhone version as on the Windows version. If a new task is created on the iPhone it does not appear in Active Actions, however when Sync'd to Windows it does correctly appear under Active Actions on Windows.
My impression is that the iPhone version is processing the "Active" status of a task in the MLO data file differently to the Windows version. One common point is that it appears to be only certain contexts. Home, Office, PRN. Though the MLO2 "Contexts and Locations" is unmodified and all are set to display in To-Do list.