Here is a file that is hopefully close to yours. Note the XY plane orientation of the Spline Mask.
Do you use the desktop or the iOS version of Affinity Designer?
There are many more options with eps files, but since I do not have the exact exports, it would be guesswork, which I try to avoid here.
I have seen too many eps files that were not written well in the past 30 years. So, I have to buy Affinity if you have more questions.
Please share your target with this workflow so that I can better help.
All the best