Action messages purely tell you there are Actions that can occur based on known data and Yes, based on how you configure them, they could be contradictory because the system needs a human to decide which Action to take based on their configuration.
For example, You have a sales order due to ship Monday January 26. but based on the last MRP run, you will not complete production by then because there are other orders scheduled to be made ahead of it. MRP may give you all of the following actions:
1) Postpone your sales order because you will not meet the ship date
2) Expedite your Production so you can meet the current ship date
3) some combination of above for lower level raw materials
You need to setup Actions based on the decisions you want planners and buyers to make. And you need to understand these Actions are based on other working times setup in your Master plans and coverage groups. For example, do I care about Actions 60 days from now when my plan will likely shift over and over again between now and then? No, so why would I set my Actions messages to include transactions more than a couple weeks out at most?
Once you dial that login into how you want to run MRP, the Actions messages will just be date or quantity-based suggestions. You do not have to make each action and taking some will eliminate the need for others.
I'd add these videos to your library and see if they help:
