I believe this button requires a particular sequence of events from X-Plane to function, and the way Xsaitekpanels is coded (using XPLMCommandOnce) it won’t trigger when using the command. I can discuss this with the developer when the time is appropriate, but there are hardware integration requests that are still outstanding from the initial release.
The CTD was reported to the CTD forum I assume?
I believe the flight plan uplink checks the nav data cycle used in Simbrief against what’s loaded in the sim to ensure referential integrity.
If you do nothing then you’ll descend in VPATH similar to a Garmin navigator. However if you want to use VVS or VFLC that’ll work too. VPATH would be SOP as far as I know.
We will need the full Log.txt to say definitively, but that extract shows this was X-Plane itself crashing, not caused by the CL-650, hence there not much the developers can do about that, unfortunately.