Realizing that 12 db is the maximum value allowed, here's what happens when I type in a value for the volume of a layer:

A single digit creates an entry of the digit followed by a decimal point and a zero (i.e., 3 creates 3.0)

A single digit followed by a decimal point creates a value of 0.0

A single digit/decimal point/second digit creates the value of 0.0 plus the first digit (1.5 creates 0.01)

A two-digit entry creates a value of the digit followed by the decimal point, a zero, and the number (12 creates 1.02)

The only way I have found to create a two-digit entry is to enter the first digit, then backspace the automatically entered digits and enter the second digit.

It is not possible to enter a two digit valiue with a decimal point.