It’s a minor bug only.
I now exported a video, and it took 29 hours 48 minutes 43 seconds for Shotcut to complete the export.
The “problem” is that Shotcut shows 09h48m43s in the Jobs panel instead of the 29h48m43s.
Well, I can live with this, just thought that it worth a report.
I experienced this just now with this job, Shotcut version is the latest stable: 18.10.08.
I don’t think that it has any to do with the system, but…
It is a Lenovo ThinkPad T420 laptop, Core i7-2640 CPU, 16 GB RAM, Windows 10 Pro English x64.