Unable to Place Block

[Beens]

I have these two spaces that will not allow me to place a block. I cannot visibly see anything in the way, I have tried swinging my pickaxe to break anything invisible or incredibly small to no avail. It is very annoying as these two blocks are keeping me from completing my base. Thank you for any help! https://imgur.com/a/r74HL4r

 

[BFT2020]

Is that a POI?  There is an issue with POIs as the quest marker will not allow blocks to be placed in that location, even if you don't have a mission there and it is invisible.

 

[Beens]

It is a broken bridge, is that considered a POI?

 

[Riamus]

It is a broken bridge, is that considered a POI?

Yes, but it wouldn't be a quest (assuming it is a vanilla POI), so wouldn't have that problem.  You would also only have the problem in one space on a given POI.

In most cases other than the cause given above, the problem is a single tiny speck of terrain that is hardly visible and is in the way.  Look very closely.  You can also just break everything around and under it and whatever might be there will fall and break and you can rebuild.

It is also possible the blocks around it are partial blocks (half blocks, etc), so there isn't actually an open space there even though it looks like there is one.

 

[Beens]

Yes, but it wouldn't be a quest (assuming it is a vanilla POI), so wouldn't have that problem.  You would also only have the problem in one space on a given POI.

In most cases other than the cause given above, the problem is a single tiny speck of terrain that is hardly visible and is in the way.  Look very closely.  You can also just break everything around and under it and whatever might be there will fall and break and you can rebuild.

It is also possible the blocks around it are partial blocks (half blocks, etc), so there isn't actually an open space there even though it looks like there is one.

Breaking everything around the area seemed to solve the issue, really appreciate your explanation and the help!