I add the Measure Segments LPE to my path which unfortunately is not correctly displayed in an exported PDF (v1.5 or v1.4). Perhaps someone may take some time to clarify at what point the problem arises.

Steps to reproduce:

I used the Pen Tool to create a regular Bezier curve with 3 segments. Now I add the Measure Segments LPE to said path. Finally I export the file in Page>Document>*.pdf.

Now the PDF only shows the uppermost 'label' that is the measure of the segment.

Note:

Upon inspection in the 'Layers and Objects' tab the curve appears within the layer 'Layer 1' whereas the LPE items are not.

Workaround:

Interestingly this may be circumvented by:

select the path
'Path' tab: change object to path (This step causes Inkscape to crash for larger more complicated files)
Note: All Measure Segments items now moved into the layer 'Layer 1'
'Layers and Objects' tab: Select only the 'text-on-' elements
'Path' tab: convert them to path

Now the export to PDF works as expected in the same way as described above.

I wil try to attach the file test.svg and test2.svg with their respective export output. test2.svg holds the content of the workaround and test.svg is a minimal reproduction example.

Some additional information on my system and peripheral software:

[bo@archlinux]$ pacman -Qi inkscape
Name            : inkscape
Version         : 1.3.2-3
Description     : Professional vector graphics editor
Architecture    : x86_64
URL             : https://inkscape.org/
Licenses        : GPL  LGPL
Groups          : None
Provides        : None
Depends On      : atkmm  boost-libs  cairo  cairomm  double-conversion  fontconfig  freetype2  gc  gcc-libs
                 gdk-pixbuf2  glib2  glibc  glibmm  gobject-introspection-runtime  graphicsmagick  gsl  gspell
                 gtk3  gtkmm3  gtksourceview4  harfbuzz  hicolor-icon-theme  lcms2  lib2geom  libcdr  libepoxy
                 libjpeg-turbo  libpng  librevenge  libsigc++  libsoup  libvisio  libwpg  libx11  libxml2  libxslt
                 pango  pangomm  poppler  poppler-glib  potrace  python  python-appdirs  python-beautifulsoup4
                 python-cachecontrol  python-cairo  python-certifi  python-chardet  python-coverage
                 python-cssselect  python-filelock  python-gobject  python-idna  python-lockfile  python-lxml
                 python-msgpack  python-numpy  python-packaging  python-pillow  python-pyserial  python-requests
                 python-six  python-urllib3  python-zstandard  readline  scour  ttf-font  zlib
Optional Deps   : fig2dev: xfig input
                 gvfs: import clip art
                 pstoedit: latex formulas
                 texlive-pstricks: latex formulas
Required By     : None
Optional For    : None
Conflicts With  : None
Replaces        : None
Installed Size  : 170.27 MiB
Packager        : David Runge <dvzrv@archlinux.org>
Build Date      : Tue 19 Dec 2023 04:57:01 PM
Install Date    : Thu 28 Dec 2023 06:44:59 PM
Install Reason  : Explicitly installed
Install Script  : No
Validated By    : Signature

 [bo@archlinux ]$ pacman -Qi cairo
Name            : cairo
Version         : 1.18.0-1
Description     : 2D graphics library with support for multiple output devices
Architecture    : x86_64
URL             : https://cairographics.org/
Licenses        : LGPL  MPL
Groups          : None
Provides        : libcairo-gobject.so=2-64  libcairo-script-interpreter.so=2-64  libcairo.so=2-64
Depends On      : fontconfig  freetype2  glib2  libpng  libx11  libxcb  libxext  libxrender  lzo  pixman  zlib
Optional Deps   : None
Required By     : appstream  cairomm  ffmpeg  gegl  gimp  gtk2  gtk3  gtk4  inkscape  lib2geom  libreoffice-still
                 librsvg  pango  poppler  poppler-glib  python-cairo
Optional For    : hwloc  libdrm  python-gobject
Conflicts With  : None
Replaces        : None
Installed Size  : 1630.69 KiB
Packager        : Christian Hesse <eworm@archlinux.org>
Build Date      : Sat 23 Sep 2023 10:50:39 PM CEST
Install Date    : Mon 09 Oct 2023 02:06:12 PM CEST
Install Reason  : Installed as a dependency for another package
Install Script  : No
Validated By    : Signature

My Kernel Version is: 6.6.8-arch1-1 (64-bit)

I did install Inkscape from the official arch repository and update it on a regular bases

 

It is common practice to convert objects that have path effects to paths (Menu: Path>Object to path) before saving a copy as pdf. 

You can make a feature request to have this take place in the background when the pdf export runs. Feature requests are managed on GitLab bugtracker: https://inkscape.org/forums/beyond/how-to-report-bugs-or-request-new-features/