Richard here - yes, we know this. The FPL-format is a simple XML format, so not a big deal normally but the main point is the AIRAC cycle which is installed in your Reality GNS …
We may not update Garmin addons, which uses the original Garmin format and that´s the point here. When you load a flightplan from somewhere, created with a current AIRAC cycle and you don´t have installed the same AIRAC cycle on your device/in your addon - it could be run into a unknown status.
Terminal-Procedures, airways, waypoints, navaids will be changed every cycle, so you can´t be sure, that your addon can use your exported flightplan because this flightplan uses newer/current data …
Also, LittleNav Map informed you during the export, that it´s necessary to use the same AIRAC as you have created your flightplan. Sorry and thanks for your understanding.