Well unfortunately the other thread is now closed, I finally got around to install a test version of v6 to test the new zone algorithm by @JeffYoung.
It does behave better, but still some glitches as in the previous version, the thermal reliefs now do come inside of the footprint area, (notice the cross in the middle).
Relief for PTH now looks like this:
And the solid, as with the previous version, works as expected.
Mixing two different zones to achieve solid pour and thermal reliefs on the same zone, still show some artifacts:
Application: Pcbnew
Version: (5.99.0-1980-gf31139ac4), release build
Libraries:
wxWidgets 3.0.4
libcurl/7.66.0 OpenSSL/1.1.1d (Schannel) zlib/1.2.11 brotli/1.0.7 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.1.1) nghttp2/1.39.2
Platform: Windows 8 (build 9200), 64-bit edition, 64 bit, Little endian, wxMSW
Build Info:
Build date: Jun 17 2020 21:06:29
wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8)
Boost: 1.71.0
OCE: 6.9.1
Curl: 7.66.0
Compiler: GCC 9.2.0 with C++ ABI 1013
Build settings:
KICAD_SCRIPTING=ON
KICAD_SCRIPTING_MODULES=ON
KICAD_SCRIPTING_PYTHON3=OFF
KICAD_SCRIPTING_WXPYTHON=ON
KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
KICAD_SCRIPTING_ACTION_MENU=ON
BUILD_GITHUB_PLUGIN=ON
KICAD_USE_OCE=ON
KICAD_SPICE=ON
Sorry for the delay 
well at least we noticed it! Thanks for your support!