Did you “generate” the OFP?
Must be done for every flight, whether it was already saved or not.
There is also a correct way to do the MCP.
So, start with the MCP.
Click on the MCDU menu, then on ATSU, in there, AOC menu, then Init/Pres.
Next go to “Init data req”, then AOC menu again.
Now select W/b, ofb request send, then boarding start.
Now from the MCP keys select INIT Request.
That should fill in the MCP.
Now go to the EFP and see if it works OK.
Hope I said all that correctly.