Legend always wrong in MATLAB R2016b

If I try to add a legend within my plots, the legend looks always strange. I tried the example code from the legend documentation. I tried adding only one or more entries. Also the work-around with 'DisplayName' gives the same strange legend-output. If I use the following simple code:

clear
x = linspace(1,5,100);

y1 = x.^2;
y2 = 3*x;

figure(1)
clf
plot(x,y1,x,y2);
legend('y1','y2')

I got this plot:

What goes wrong with my Matlab and how can I fix it? It is no sustainable solution to set all the individual parameters for every single legend entry. I'm thankful for every support.

[KALYAN ACHARJYA]

I don't have 2016b, in 15b its works perfectly.

x=linspace(1,5,100);
y1=x.^2;
y2=3*x;
figure(1)
clf
plot(x,y1,x,y2);
legend('y1','y2','location','northwest');

Answer 1

[madhan ravi]

Read the below link:

https://www.mathworks.com/matlabcentral/answers/332155-problems-with-legend-in-r2016b

[Tino]

Adding a 'Location' like proposed is not helping. There is sill "Warning: Error updating Legend. not enough input arguments" with the same strange legend.