From the manual, I understood that that was resolved with Version 0.1.4 of the Caravan. I reinstalled 0.1.4(a) just now. WT 530/430 is up to date. The flightplan in question is the one from yesterday’s Community fly-in (which I downloaded here), but it also happened with selfmade ones. I’ll quickly disable WT’s GPS and check.
Edit: with just WT’s GNS430/530 (v. 1.1.3) installed, flightplans are shown but the Garmin startup is omitted.
Using 1.1.4 alongside will obviously cause the error.