Colors on CMYK JPEGs reversed

I've created some works in CorelDraw X8 and exported them as JPEGs for submission and it was required that all images must be in CMYK format. I was about to email them when I noticed that the colors had gone wrong (see image below). Concerned that there must've been an error in the program, I've reset CorelDraw X8 to the default setting but the results were still the same. I've asked a colleague to open the CMYK Jpeg files for me using a popular photo software program and the colors were fine and correct, even though the thumbnail showed otherwise.

This somehow happens only with CMYK files. I've tried exporting them in RGB format and both the thumbnails and image file were fine.

Can anybody tell me what's going on, and how do we fix this? I want to make sure this issue won't affect the files once I've sent them.