My partner has Navigator v7.2.60 with OSM maps running on an Huawei MediaPad M5 with Android 9 and is unable to save routes. I tried this on my Honor phone running Android 10 and experienced exactly the same issue.
I also have a Samsung tablet that I usually us when touring in my motorhome v7.2.43 (Truck) with Android 7.1.1 but have no issues.
Is this a problem with 7.2.60 or some sneaky thing with Huawei/Honor?
I have 7.2.60 running on a S5 with Lineage 17 and on a S9 with Android 10, no problems on both. What do the rebellious devices say when trying to save routes?
It seems to save tbe route which appears in the list but after logging back in again it is not there. I've tried this several times with the same result
Is it an imported route or was it planned in MFN? Imported routes will appear in gps recordings if the gpx file is not a route but a track.
If it is a route planned inside Navigator my first approach would be a look at the routing_points.xml file (where the routes are stored) for any write protection.
Next approach would be delete cache and user data. Please backup first, You could loose Your data.
Other experiment which I didn't try yet would be to delete routing_points.xml. I can imagine that MFN will create a new, empty routing_points file and present You an empty list after being fired up again. Then try to create a new route inside MFN and try to save it.
With all experimenting, don't forget to backup first. Preferences and other features can be backupped with the internal option, maps can simply be copied to another directory and moved back.