Fenix 6X Pro - why do my GPS tracks have straight line sections?

GPS was set to GPS + GLONASS not Ultratrac. I'll try and find a tool which allows me to examine the file data. If you know of one then I'd be grateful if you could point me at it. I can understand why you think that section was recorded in ultratrac mode as there are a series of straight lines. However that's the fault I'm describing. There are other sections of the route where it's recording every wiggle. Here: connect.garmin.com/.../8101227036

Forget about thinking it’s in ‘Ultratrack mode’ unless it’s doing it all by itself. As I said before, my settings are the same as yours and the issue persists. Wait and see what Garmin says… (I gave up with mine )

Have you upgraded the firmware?  I'm now on 20.30.  I've recorded one track since the upgrade. A mountain hike, it was over 5 hours long. Any straight-line sections aren't obvious enough for a Garmin employee to spot! https://connect.garmin.com/modern/activity/8211562476
There are little straight sections but they are small enough that I can't be certain if that's the recording, or the resolution of the map, or what I actually walked.  More tests required. 

I won't be contacting Garmin until I've got tracks which clearly show straight-lining with the new firmware. I'm recording tracks with my phone and an eTrex too for comparison. They will help identify the errors. The eTrex 20x has always been solid.

I have the feeling that it is a firmware issue because the watch's 'time to first fix' is good. That suggests both the aerial and GNSS receiver are working OK. Where it does not straight-line the track is good (which is most of the time). 

We're not alone. This reviewer had the same issue on top of a hill.  "The fenix 6X Pro delivers a very satisfactory result on the mountain tour – especially in comparison to the handheld device – but shows a few "dropouts" at the points marked with waypoints. The track runs straight ahead, even in places with the best GPS reception (summit area). The firmware developers still have something to do …!" www.navigation-professionell.de/.../

Okay, it's not a setting issue than. Even if the lines are straight the recorded points are seem to be recorded every second. So maybe some algorithm or some issue affected it. And that review saying it draws smooth lines on summit interesting, too. I'm two years 6X Pro user and haven't had such smooth tracks in such activities. 

There are some tools in Garmin's Fit SDK. developer.garmin.com/.../ I converted your fit file into CSV file using FitCSVTool.jar in Java directory. It creates a very big file. At some points lat keeps going same while longitude changes. And at some points speed is very slow. It's only you who knows how you walked the track and where the data is wrong.

I'll try and get a human readable CSV file myself, then I can see if it's getting things wrong. I'd be surprised if I walked in such a straight line that the lat stays the same. If that happened when I was walking north-south then that must be a fault. If it was on an east-west section then maybe that happened....

It's straight-lined on Y Garn for sure. You don't get a much more open sky than on a ridge crest! Just curious...how were you recording data?  Smart or 'every second'.  I could understand a little smoothing when using the smart setting but I've had straight sections using both settings. Significant variations in my track went unrecorded or wrongly recorded.  It doesn't help that the original FIT files can't be opened in a text editor. That's my next task....learn how to examine the original recorded data in a human readable form. GPX file exports won't necessarily transfer the data point for point....although they might!

I havent looked at your data in the .FIT files but i suspect that you walk really slow with a very low cadence from time to time. I have seen strange behavior under those condition.

A cadence below 60 per minute (below 1 per second) in combo with low GPS speed seems to trigger some kind of timeout after a while (even if auto pause is off). I have seen it this autumn while I was mushroom picking. Then, after a while when cadence and/or speed increases it starts working again. And results in straight lines in GPS trace. A bug in the software i guess.

Interesting.....  nearly all my outdoor time is in the mountains. My walking speed of necessity will be slow...especially when going uphill. I suspect a firmware issue causing the straight-line sections. I don't know why the designers would ever build in any 'timeout' when the user actively chooses 'every second'. I just want a point recorded every second with no firmware fiddling!

I shall bear your comment in mind when looking at future tracks.

I dont know why the software acts that way. Either a bug or "by design". I can reproduce the problem by walking really really slow with a very low cadence for a while. For me it has nothing to do with GPS reception. The device probably "thinks" that you standing still and that the GPS movements is due to GPS drift.

The software work in 1 second steps and if cadence is below 1 step per second it will have problems to identify it properly.