Via Stitching places 0 vias

[n8ur]

I have a 4-layer board with 3 layers having ground pour and one layer having Vcc pour. I am trying to stitch ground vias and no matter what settings I try ViaStitching returns successfully but reports placing 0 vias. I have other boards where stitching works properly, so it must be something about the board settings for this board. I've tried various clearances and hold/via sizes but nothing changes the result.

Any suggestion what I should be looking for?

Running KiCad Application: KiCad PCB Editor x86_64 on x86_64

Version: 7.0.9-7.0.9~ubuntu22.04.1, release build

Libraries:
wxWidgets 3.2.1
FreeType 2.11.1
HarfBuzz 6.0.0
FontConfig 2.13.1
libcurl/7.81.0 OpenSSL/3.0.2 zlib/1.2.11 brotli/1.0.9 zstd/1.4.8 libidn2/2.3.2 libpsl/0.21.0 (+libidn2/2.3.2) libssh/0.9.6/openssl/zlib nghttp2/1.43.0 librtmp/2.3 OpenLDAP/2.5.16

Platform: Linux Mint 21.2, 64 bit, Little endian, wxGTK, cinnamon, x11

Build Info:
Date: Nov 8 2023 19:01:25
wxWidgets: 3.2.1 (wchar_t,wx containers) GTK+ 3.24
Boost: 1.74.0
OCC: 7.5.2
Curl: 7.88.1
ngspice: 38
Compiler: GCC 11.4.0 with C++ ABI 1016

Build settings:
KICAD_SPICE=ON