First layer cracking

[sebasd]

Hi
I have a strange problem when printing a large object.
The first layer cracks up.

The brim is perfect and sticks very well, but when the bottomlayer is printed, take a look at the image.....
Why does this happen?

Line width is set to 0.32mm
Height 0.3mm (initial layer, all other 0.2)
Temperaure 210
Bed temperature 55 or 60, happens at both temperatures.
Standard speed settings.

As you can see the brim is very well fitted to the bed.

Have been able to print this size before without any problems.

The print bed is very clean. I use the magnetic bed.
PLA is geeetech

[OrazioGiunta]

it seems your nozzle hit the bad, have you checked ?