Get close and try a metal detector to find pins if you have them.

Western Wildlife Services

You can send them a message to have it fixed.
Just like every other app out there, they go by tax assessors records. If the counties records aren’t updated, then the apps aren’t.

If the corner posts are there it should get you close enough to find them easier. I was able to use it to find the two back posts of mine. Correct me if I am wrong but didn't OnX say in the beginning that it was accurate to 3 feet. Thought I saw something about this years ago. That they guaranteed it's accuracy. Probably wrong..... Yep

I mapped a flowage with a Garmin handheld GPS when it was drained for a dam repair, I learned a lot because I was marking sunken fish cribs- even with the Garmin you would have to wait for the satellites to triangulate your position- the advantage was the Garmin would show the accuracy detail, Accurate within 15 feet- if you stood still for a moment it would say accurate to within 0 feet and you then dropped the waypoint. Last year during ice fishing season I dropped multiple cribs on OnX based on my Garmin waypoints- I could go there today and drill a hole on top of a crib. The accuracy is there unless like I mentioned- you drop a waypoint and keep walking- I've had to delete multiple waypoints for this reason when I first used it.

I have the Elite OnX membership and I don't think it matters what level you have in terms of accuracy. With the higher plan you simply have access to more states and more functions. I would not rely on it for survey work in terms of standing up in a court case. However, as has been stated if you give it a few seconds to figure your location I have found it to be as accurate as I need it to be for a variety of uses.