Solved
win10, classic 5.0.637
input 3 functions: sin(x), 2^x, ln(x)， save it, and close the window.
double click the file and re-open the file, only 1 function left in the 2-D view. the other 2 functions disapper.
but, if i use geogebra menu File--Open Recent file, open it , it does have 3 functions!
Files:
bug-2fun-disapp...
The same problem 
PS: if I only input one function: sin(x). it has the same problem.
Better with this version? http://test.geogebra.org/~m...
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