Hello Alex,
may you please share a GPX file you try to import? Or at least a part. There will be some basic problem, that cause coordinates are not imported correctly.
Also you may use "loc" format. For example my_points.loc file should looks like this
<?xml version="1.0" encoding="UTF-8"?>
<loc version="1.0">
<waypoint>
<name><![CDATA[Name of waypoint]]></name>
<coord lat="50.184" lon="14.658" alt="100.0" />
</waypoint>
<waypoint>
...
</loc>
Anyway support for altitude won't work in current 2.19.0 version. I've just did it, so you have to wait on next update within a week