Hello,
From the Table 10-1 of ISOW1412 datasheet, I understand that to expect Visoout = 5V, the VDD pin cannot be supplied by 3.3V typ but should be supplied from 5V typ.
While in Table 8.2 of the datasheet, the range mentioned for VDD is 3V to 5.5V. Since the mode is not mentioned, this data conflicts with Table 10-1.
Please share the operating range of input voltage for VDD pin while Mode pin shorted to Visoout to expect Visoout = 5V.