Hi there,
I've recently opened a ticket with Lezyne's support to sort out the issue with spotty navigation.

What I have noticed was the unreliable navigation feature when dealing with long GPX files. After reporting that to them, they obviously suggested me to update the firmware but it resulted in navigation not working in most cases anymore. Resetting the device on top of resetting the Ally App didn't bring any good either.

I've provided them with my track file - 113.48km (70.5 miles), which apparently has 2200 track points in it (but only 206 KB of size), however, they are kind of reluctant to test the file on their end.

Can anyone of you try it out with your Lezyne GPS? Are you able to push it to the device and see the breadcrumb screen?
Here is the link to the GPX -> support.lezyne.com/attachments/token/KCBu7THijk1lZX9gaHnz859Ya/?name=Zbiornik+%C5%9Awinna+Por%C4%99ba.gpx