[Bug] Keeps freezing

[Tugdual]

I tried that... didn't work.
Here is how I kill the Prime, seems to be reproducible all the time:
1. go in CAS and make sure you're in radians
2. enter

Code:

series(tan(x),x=0,20)

You should now see $$x+\frac{{x}^3}{3}+2*\frac{{x}^{5}}{15}+17*\frac{{x}^{7}}{315}+62*\frac{{x}^{9}​}{2835}+1382* \frac{{x}^{11}}{155925}+21844*\frac{{x}^{13}}{6081075}+929569*\frac{{x}^{15}}{63​8512875}+6404582*\frac{{x}^{17}}{10854718875}+443861162*\frac{{x}^{19}}{18561569​27625}+x^{21}*order\_ size(x)$$
3. Copy the former line and change the end so that it reads:
$$x+\frac{{x}^3}{3}+2*\frac{{x}^{5}}{15}+17*\frac{{x}^{7}}{315}+62*\frac{{x}^{9}​}{2835}+1382* \frac{{x}^{11}}{155925}+21844*\frac{{x}^{13}}{6081075}+929569*\frac{{x}^{15}}{63​8512875}+6404582*\frac{{x}^{17}}{10854718875}+443861162*\frac{{x}^{19}}{18561569​27625}▶f(x)$$
4. Press enter and now move into the Function App
5. Symb, enter F1(X)=f(X)
6. Plot
7. Mess around with fingers like zoom, scroll, after less than 5 secs, the Prime is frozen.
8. Now On-Symb it, go back to CAS, all is gone... Even f(x) is set back to an earlier definition which is pretty weird because it means the Prime is doing backups!

Note: This is just an example demonstrating the issue, as I mentioned I keep getting it a lot.