I think you can have only one OPTION for the partition table map scheme which is for the entire drive.
So, when you created your two partitions (1.5GB Mac OS Extended - Journaled format and a 2nd for the rest of the space as ExfFat format) you chose the partition table map scheme as GUID, Windows will not see either partition. For Windows to see the ExFat partition, the partition map scheme has to be Master Boot Record.
I have never formated two different partitions like you and made the partition table map scheme Master Boot Record. I know the PC will see the ExFat partition, but I don't know if the Mac will see the other. Understand you won't be able to boot from the Mac formated partition since the drive is MBR. Try it! You will need to reformat the drive with your two partitions when you change the partition table.