Korean font written in textbox disappears once saved a PDF

I have a 3.2.4 of DocuSeal installed on an LXC. I installed during 3.2.2, so many of the setup was during this period. I just updated to 3.2.4. Using an iPhone iOS 26, I can edit fine, but once I input the information, anything in Korean disappears.

root@docuseal:~# fc-match :lang=ko
NanumGothic.ttf: "NanumGothic" "Regular"

My PDF file shows

Application: DocuSeal (https://www.docuseal.com) PDF Producer: HexaPDF version 1.7.0 PDF Version: 1.4 Fast Web View No PDF Optimizations: PDF/A (ISO 19005) Number of Pages: 1 Page Size: 8.26 x 11.68 in (A4)

Fonts: Dotum (TrueType (CID); Identity-H; embedded) DotumChe (TrueType (CID); Identity-H; embedded) Helvetica (Type1) Helvetica (Type1; Ansi) T3 (Type3; embedded) T4 (Type3; embedded)