Vtol, loss of altitude during the initial stage of flight

Hello. I can’t understand my problem with my VTOL. The flight controller is installed pixhawk orange. I take off in manual mode as a quad. I gain altitude of 40 or 50 meters. I switch to cruise mode. The plane starts a normal flight, and then there is a sharp loss of altitude of 15-20 meters. Then the altitude is not lost. The plane gains the required altitude and flies according to the mission normally. I tried to take off in auto mode. The plane gained altitude according to the task of 40 meters as a quadcopter, then switched to airplane mode, after that the altitude loss is 20 meters. Then leveling and gaining altitude according to the task. This happens every time during takeoff. I can’t understand the problem. Please help. Thank you.
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Please post a .bin log. It can be caused by a too aggressive transition settings leading to transition before minimum airspeed is reached.

Thanks for your reply. I will add my VTOL settings file now. Next I will add one of the flight BIN files.
Prochivka.param (22.3 KB)

Unfortunately my BIN files are too big, there is no way to upload them here. The smallest is 74mb, and here no more than 44 are allowed.

Use popular file sharing service like Google Drive, DropBox, Mega.nz…

At first glance, it seems like the CG might be incorrect, possibly shifted forward. But please upload the BIN file so we can take a closer look.

Sorry, I somehow didn’t think about it. Here is the BIN file of one of the flights. https://drive.google.com/file/d/1V_6HP2bj1pD2X8ih28Q4aNcJB28mwkQb/view?usp=sharing

The centering is correct. Before each takeoff I hang the plane. The problem confuses me. The plane takes off well as a copter. Then it switches to airplane mode. It flies well and smoothly and then abruptly lowers the nose and loses altitude. Having lost 15-20 meters it levels out and begins to gain altitude again according to the flight task.

your bin file only has QRTL and QSTABILIZE

I will fly on Monday. I will send a new flight file. I changed the parameter Q_TRANSITION_MS, made it 5000. I will check, maybe this will change something.