Created new Vanilla 1.14.4 world.
Added a custom datapack with a .mcfunction (eg: sayhi.mcfunction)
Edited server.properties, set op-permission-level=1 AND function-permission-level=1
Restarted the server, signed in, confirmed the datapack loaded properly.
Used admin console to /op my character.
Running a second time confirmed the success ( [Server] Server thread/INFO Nothing changed. The player already is an operator )
Confirmed with ops.json file that my character is "level": 1 – as generated by the server.
Typing /function in game gives: Unknown Command
If I am rank 2 OP and function-permission-level (FL to save typing below) is 2, /function works.
If I am rank 2 OP and FL=1, it works.
If I am rank 1 OP and FL=1|2|3|4, it fails.
My assumption here would be Rank 1 OP is lowest permissions, Rank 1 FL would be added to Rank 1 OP. Rank 2 OP = FL2, Rank 3 OP = FL3, Rank 4 OP = FL4, etc
It appears that changing function-permission-level is not affected by OP rank. Was this intended?
function-permission-levelregulates what commands functions can execute, not who can execute functions.