Solid Hardwood, Engineered and Laminate Flooring - How to level plywood sub-floor?

(Apologies if this turns out to be a duplicate question. I tried to post once already but it doesn't seem to show up on the board.)

I will be installing Bruce Hardwood flooring on a plywood sub-floor that sags a little in one area - not more than a 1/4 inch - just enough to notice when you walk on it. I would like to know what my options are for leveling this floor. I have worked with cement-based leveling compounds before but don't know if that is a good idea here as I need to use something that will accept nails or staples when hardwood is installed. I can go under the house and see if I can raise the level of the joist, with a shim possibly, but would like to know if there is a leveling compound (that accepts nails) that I could use instead? Any suggestions would be appreciated. Thanks.

Build the low spot up with layers of rosin paper or roofing felt. If it is deeper then you thought, oll roofing works.

Or you can break out the sander and sand down the high spot.

I am going through this myself, I just lifted the plywood and put roofing tiles over the 2x10's to level off and then screw the ply back down.......

I also need to insulate some of the floor anyway.