Hi,
I had the same problem, but I discovered that the issue is not with "Wrong Color", it has to do with the type of the curve being copied.
Look at my example below, I created a red bulls-eye (hollow inside) and tried to copy the color from the blue square - corel closed the it !
But if I add the blue color as a style - it will work.
WHY ? I DO NOT KNOW !!!
I am sure it is a bug in both X6 Update 4 & in X7 update 4
I think I know what is happening: When you copy the fill from another object, the winding rule is copied too.
The original object has "Fill winding" (Object Properties docker, Fill tab) disabled.This means that even if the subcurves are running in the same direction, the "hole" will be shown unfilled.The object you copy from has "Fill winding" enabled though. The hole will still be there but because of the new fill rule, it will now be filled too.
Read about winding and fill rules here and here.
Actually I finally solved it - The incident happened again when I imported a PDF that was exported from an EPS in Adobe Illustrator that showed weird nodes. Although the above was totally done in Corel.The whole issue is so stupid, I tried clicking "Reverse Curve Direction" and it worked.
I think it is a bug that can be solved this way !
Sorry to tell you that there is no interlocking or winding and it still happens - I found the solution below. To simulate the effect try cutting out (Trim) an Alphabetic Character like an "A" out of a Square or a Circle, it may happen with some fonts.
But I solved it, "Reverse Direction" would fix the issue.
Still need to know why? - Corel has to answer for that !
Not a bug just the way it works, I would have broken the curve apart and filled as needed.