autocompletion disappears for 3 character variable with Upper case when input lower case

[xgdgsc]

For example, a variable named tU0=1.

when I input tu0 when 0 is input, the auto completion disappears. Hope it would still show so that I could enter to correct the lower case.

And if it' s a four character variable like tU01 it would not appear after input tu01 but it would disappear after input tu0, which is also not ideal.