Can’t select some houses/lots

Could you post a screenshot of what you're seeing?

Do you have any mods or custom content (CC) in your game? Could you test without?
You can just move the folder to a location outside the Electronic Arts folder.
If the game works without your CC and mods in, your issue is probably caused by a broken mod or CC.
You can find a full list of broken/incompatible CC and mods since game updated on November 13th over here:
https://forums.thesims.com/en_US/discussion/950909/broken-updated-mods-python-terrain-update-get-famous-nov-18/p1

This update, updated the coding for mods so most mods need updating.
If it still doesn't work I suggest taking out half of your mods and CC and testing the game. Then keep splitting until you find all that is broken.
Either update or remove the broken CC/mods. 

I don’t have any mods or cc at all.

Ha those diamonds are called plumbobs. That seems normal, it sounds a little like you're clicking next to where you want to click. 
Could you try playing around and see if that is the case at all? It could be your mouse is just a bit out of whack?

No, it doesn’t matter if I switch to another mouse or use the pad, same problem. The mouse work fine.  I tried to post a film clip to show the problem but I didn’t manage to do it.

When I click(or hold the cursor) on the houses (inside the square) nothing happens. On all other lots the square lights up, but not here. When I click on the plumbot (thanks for the name) the plumbot from the house above “come down” and that lot’s square lights up (the wrong ones).

So I can choose those neighbor houses “from two spots”; the real ones and theese “fake ones”. The actual houses on the lots can’t be reached.

You haven’t heard of this problem before?