Fixed the problem!!
In case someone else is looking for the same thing:
Find the folder on your device that contains the files navobj.xml* files In my case there were several of these files and when I looked at the biggest (most kb), I saw all my waypoints. That one was called navobj.xml2 I renamed that one to navobj.xml after I checked that one indeed didn't contain any info.
Make sure you CLOSE OpenCPN
BEFORE doing this. Then, when starting OpenCPN
, it uses the correct file and all the waypoints and routes are there again
To be sure not to lose anything, copying the text of the good xml file before renaming it, might be a good idea.
P.S. It must be a bug that this happened. Do developers read here?