How to make the hours display in the payslip,
You mention that for "one wagetype the hours are displayed in payslip", implying that the (number of) hours are not displayed for the other WTs.
First, check in the RT if hours exist only for that WT or for all other WTs.
If hours exist only for that WT in RT, then you should check where in your Payroll Schema the hours are deleted from the other WTs (or where the hours are added for this WT), and make the appropriate corrections.
If the hours exist for all earnings WTs, then the problem should be in the Line Type that is used to display that WT in the Payslip/Remuneration Statement. Use t-code pe51 to compare that WT with a similar one, and make the appropriate correction.