Structure 2 can't find samples when moving/copying zones

[TPB3333]

Hey I just got structure, and although I like it it doesn't let me copy a zone and then paste it. It gives the error that the file/sample is missing, while I just copied it from the zone beneath it.
I saw a few other people online experiencing this. I don't think it's a bug with my system. But I'll give some specs anyway.

I use Reaper and I work on a custom desktop running on Windows 10:
Processor (CPU) Intel® Core™ i7 with quadcore i7-7740X (4.3 GHz) cache of 8 MB
Motherboard ASUS® PRIME X299-A: ATX, USB 3.1, SATA 6 GB/s, suitable for RGB
Memory (RAM) 32 GB Corsair VENGEANCE DDR4 2400 MHz (2 x 16 GB)

Regards
Toon