Selecting Export flight plan and then selecting X-Plane 11/12 (.fms) brings up the window shown below
Everything is untouched and shows the save as file type with 2 periods (*…fms). Notice the extra period. On the File name line it shows DEPTARVL.fms…fms which is not right. It will show up in X-Plane as
There should only be a single instance of .fms in the line. Everything else is not needed.
Is there any way that the default filename could be DEPT-ARVL (with a dash between to two airport names)? Notice in the Flight Plan listing how much easier it is to read/search for the flight plan that you are looking for. I have been using this convention of naming my flight plans for years and I ALWAYS have to change it to my naming method.