I se alot of underground rocks. its know that items under the ground prefent building . I would scrape away the land to check it and if needed pick away the rocks whit a pickaxe.

I can be wrong ofc ..

I can't do anything in the area, I can't even clear the grass. I've destroyed the few rocks lying around as well.

Had a Guide come and check it out and we both thought it's the big rock sticking through the ground causing the problem

hm yea could be, I had a error when i accidentally flooded my land. the game made a dirt dam to protect the rest of land from the water but made the dam over my items (bins and tent) as there was something under this new dam (my items) i could no longer dig or build there as "something" was in the way.

I warned the guide's (mihr) for this as it could potential destroy large areas of land unable to use it for anything ever.

Solution would seem to allow digging on spots that already have something on or under it but that could cause several other issue's (ppl removing sand under logs to make bridges being a" good" use of it..,but one can Imagen the abuse..)

seems your land area has the same type of "bug" ony created by the game and not man made like mine.

I have the same problem. If there is an object nearby, it actually affects an area much greater than when the object itself is. I would recommend that they shorten the distance that an object affects the ground around it (I don't know how to say it technically).