Plotting issue on square mesh

Hello,
I just installed the FreeFem++ v4.11 on Linux Mint 20.3 on my new machine.
I was testing the codes in the examples and encountered segfault with plotting on a square mesh.

For example, this code produces segfault when it comes to the plot line:

mesh Th = square(150, 50, [3x, y]);
plot(Th,wait=1);
fespace Vh(Th, P1);
Vh u;
u = cos(2.0
pixy);
plot(u,wait=1,cmm=“initial field”);

However, if I set u = const, then there is no segfault.

On the other hand, this code goes through fine:

border C(t=0, 2pi){x=cos(t); y=sin(t);}
mesh Th = buildmesh(C(50));
fespace Vh(Th, P1);
Vh u;
u = cos(2.0
pixy);
plot(u,wait=1,cmm=“initial field”);

Any ideas on what could be going wrong?