Random parts of floor becoming unwalkable?

Wonder if you have some invisible objects there although those should go away if you delete the floor tile.

Can you try building a room around the tile and maybe one or two adjective ones and then delete the room ?

Hello! I've tried to build a little room around the unusable tiles, but it doesn't seem to work. I've found that the glitch can now happen on every [residential, at least] lot type, and always typically near a corner. I'm not really sure how to fix it, I just hope it's not tied to that scary game self-deleting bug going around😓

AnemxiaWasHere  To better help you, it would be helpful if you would post some pics of what you have going on.  

There are 2 things that I know of that will cause blocked tiles.  The first is invisible objects blocking the times as crinrict mentioned.  The fix that usually works is to redraw the room using either the wall tool or room tool.  Move everything out of the room first including anything on the walls, then trace the outline of the existing walls.  Then, you'll need to repaint the walls and replace the floor tiles.  Check the tiles that were blocked by sending a sim to walk over them.  If everything is ok, then move all the items back into the room and you are good to go.

The second thing that can cause blocked tiles are intruding roofs.  Usually, it happens on 2nd or higher floors where part of the roof is inside the room.  The fix is to check the roof and make sure that it stops at the adjacent wall rather than extend into the room.  Sometimes, this will mean you'll have to redo at least part of the roof on the build if there are gaps in it after you change it so it doesn't intrude into the room.

Since you seem to have this going on in multiple venues, it might be how you are building the lots or how the creators built the lots if you downloaded them.  I've seen the roof issue a number of times here in various builds I've tested so I know a lot of people have done that. 

That said, if you still can't get the blocked tiles fixed after redrawing the room or changing the roofs, I am willing to test one or more of your lots with the problem and will see if I can find the problem and a fix.  All you need to do is upload the lot or lots to the Gallery and after doing so, reply here with the lot names and your userid if different from the one you use here (AnemxiaWasHere) to let me know that you want me to do that.  I'll download and test and get back to you in a day or so.

Hope this helps.  

Hello! I'm so sorry for the extremely late reply, but I just came to report that it's not something with the game it turns out - the builds I was living in and/or playing on had strange invisible objects set in in odd places. If I drag the delete hammer across it, it usually fixes the issue from my experience so far. I really appreciate all the help :)