Seat Leon 1.9 TDI 2008 clutch or gear box problem?

[Diver Izrod]

Hi. I'il describe the problem briefly. When the engine is turned off, the gear change without a problem. However, when I start the engine and switch to the first gear, the clutch pedal fails and the gear lever locks. After I turn off the engine and manually lift the clutch pedal, again everything is fine.
Is this a gearbox problem or a clutch problem?

Thank you very much