Can't view filled zones

On MacOs Big Sur with KiCad Version 5.1.9-4-g58460db46 pressing the show filled areas in zones button is doing nothing:

What net have you assigned the fill to?

And have you pressed ‘b’ to refill the zone?

Hi Naib, I’ve assigned it to the +5V net

I didn’t press “b”. but I did the refill zone from the context menu. Is there any difference?

Is there a pad that has this same net assigned inside the area that you want to fill? I mainly ask because at least some of your components do not seem to have a refdes which might indicate that you work without a schematic.

The LED is connected to a “GND” net and the resistor a "+5V"net but that’s about it.

the “+5V” net is a THT pin so on both copper layers and the zone should fill with either the B key or Pcbnew / Edit / Fill all Zones

The simplest way to diagnose is if you zip the whole project and post it here.
You can remove backup files and the fp-info-cache (which is multiple MiB sometimes) but include the [projec]-cache.lib.

Not as far as I know. ‘B’ and the menu equivalent are the same.

I would really encourage you to try and work with Kicad rather than against it - especially if you are just starting out. You will find that drawing a schematic first and then laying out the board is the expected workflow and will avoid some potential ‘gotchas’. People argue ‘well, its such a simple board I don’t need a schematic’ however, without a schematic you don’t have a netlist so you have no DRC check. The other argument is that it takes too long - but such a simple design will take you two minutes to draw - it doesn’t have to be perfectly laid out. Furthermore, when/if you move onto more complex designs, you will have some experience with the layout editor too. It also makes it easier to help someone if they have a complete project to zip up and post.

If there was no schematic at all, then where do the two net labels come from?
If there was a decent schematic, then why are the other pins not labeled?

In KiCad there is no automatic synchronisation between schematic and PCB. If changes are made to the schematic, you have to update the PCB with: Eeschema / Tools / Update PCB from Schematic [F8].