<!-- --------Before Creating a New Issue----------- * Limit report to a single issue. * Search the issue tracker to verify the issue has not already been reported. * Complete all instructions between `template markers <>. * Keep report contents limited to the necessary information required to fix the issue. ---------Add your issue details below----------- --> # Description <!-- What is the current behavior and what is the expected behavior? --> I’m trying to length match a pair of traces using the Route > “Tune skew of a differential pair” tool. The tool has worked fine for about 6 pairs already on my PCB but is now producing strange skew values and interpreting the wrong track in the pair as the shortest. As an example, the lengths of my tracks HDMI0_D0_N and HDMI0_D0_P are 62.4240mm and 65.1077mm respectively but the skew value is shown as 14.1054mm. Please see screenshots showing the length of each track and also the reported skew.   <!-- If the issue is visual/graphical, please attach screenshots of the problem. --> # Steps to reproduce <!-- If there are multiple steps to reproduce it or it is a visual issue, then providing a screen recording as an attachment to this report is recommended. --> <!-- If this issue is specific to a project, please attach the necessary files to this issue. --> An archive of my PCB project is attached. [PiCamera.zip](/uploads/148696d7cf5d70491d6348f26d5099eb/PiCamera.zip) # KiCad Version <!-- Copy version information (from main menu Help->About KiCad ->Copy Version Info) and paste it between the triple backticks below to preserve the formatting. --> ``` Application: KiCad PCB Editor Version: (5.99.0-9568-gb9d26a55f2), release build Libraries: wxWidgets 3.0.5 libcurl/7.71.0 OpenSSL/1.1.1g (Schannel) zlib/1.2.11 brotli/1.0.7 libidn2/2.3.0 libpsl/0.21.0 (+libidn2/2.3.0) libssh2/1.9.0 nghttp2/1.41.0 Platform: Windows 10 (build 19041), 64-bit edition, 64 bit, Little endian, wxMSW Build Info: Date: Mar 3 2021 21:58:32 wxWidgets: 3.0.5 (wchar_t,wx containers,compatible with 2.8) Boost: 1.73.0 OCE: 6.9.1 Curl: 7.71.0 ngspice: 34 Compiler: GCC 10.2.0 with C++ ABI 1014 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 KICAD_USE_OCE=ON KICAD_SPICE=ON ```