Normal map only working on first swatch? [SOLVED]

Hi there!

I'm currently working on a conversion headpiece (for those curious: headpiece from the Plague in Dead by Daylight) that is doing something strange I've never encountered before.

I made two versions of the same headpiece: one with strings (the 'original' one), and one without.

The version of the headpiece without the strings is working just fine: the normal map shows on every colour swatch perfectly. However, the 'original' version of the headpiece only seems to display the normal map on the very first swatch, but not on the other colour swatches. I've tried to re-do the entire thing by cloning and reimporting everything again, but the same result: normal map just shows on the first swatch, and nowhere else. I'm just confused how it seems to be working on a identical headpiece (minus the strings), and not on the original one. Everything seems to be the same, but I can't figure it out.

Some pictures to illustrate the problem:

Thanks for reading, it's really appreciated!