I have entries on my 1099-B where "Wash Sale loss disallowed" is a decimal value and Turbotax default to "0." and will not let me enter the decimal value or even a 1.

A disallowed wash sale loss of less than 50 cents gets rounded down to zero, so there is no wash sale. You can't correct the problem in Smart Check where it displays the error message. You have to go back to where the sales were entered under Investment Income > Stocks, Mutual Funds, Bonds, Other. Edit each sale and delete the wash sale loss amount, leaving the box blank. In other words, since the wash sale loss is less than 50 cents, you don't report it as a wash sale.