Where you reported your quad glitching (this is at the 02:41 fly time mark in your DVR), this coincides with momentary RX signal loss events as you can see by the yellow graph line at the bottom of the image below where the vertical red line goes through it. This will be triggering stage 1 of a failsafe which then recovers quickly enough before it goes into a full (stage 2) failsafe. There are quite a few more of those RX signal loss events throughout the log and if I slow the video down, every time one of those occurs, there also appears to be a momentary stutter in the video. It's more obvious when you're doing a sharp manoeuvre like at 02:41.

So it looks like you still have some issues or a fault with your receiver. If you're sure all the connections and the antennas are fine then I would just get a new replacement receiver.

Click on the image below for a full size view.




EDIT: And this is a video of the same with the blackbox overlay. Keep an eye on the yellow graph line at the bottom. The first RX signal loss glitch is at 1:36 into the video (01:34 on the DVR fly time). You can use the YouTube options to slow the video down if you need to.

Before you go replacing the receiver, I had a thought while I was on the train coming into work this morning.

It looks like you're flying in some kind of shopping mall. Maybe there is a high noise floor there, or a lot of other interfering traffic on the 2.4GHz band which is causing your momentary RX signal loss problems. It might be worth you going out somewhere to the suburbs away from any buildings or habitation and recording a new blackbox log to see if the glitching problem disappears or if it still persists.

true that :S that is a soccer stadium and now I realize that on the top of the stadium light is some sort of the antennas... maybe that's it... I'll try to go elsewhere and record black box I hope that is the problem. Thank you SnowLeopardFPV you are a true help to me in my process of building if you ever come to Croatia you got your self a beer or two haha

Those antenna's are GSM cell tower masts which will be broadcasting on the 900MHz frequency, so they shouldn't be interfering with the 2.4GHz band of your RC link. Looking around that area, it doesn't actually look like the sort of place where there would be a lot of RF interference anyway, so my money is back on the cause being a dodgy receiver.

https://www.google.com/maps/@45.5438022,18.6945244,3a,90y,33.64h,120.82t/data=!3m6!1e1!3m4!1seBzpzfJGKjF4v-ifh_b7Xg!2e0!7i13312!8i6656

Maybe go back to the catacombs and have another fly around there to see if you get the same behaviour, because I don't believe you had any issues there on your maiden flights.

I can inform you that the receiver is fine, this weekend I was at my parents village so I tested the drone and everything seems fine reception was good and glitches are disappeared. I can upload some DVR from there. 3D printer is arrived too so I will print some GoPro mount soon.

If you haven't already done so, take a look at your blackbox logs to ensure that the RX Signal Received value never momentarily dropped like before because even in your last video some of those RX Signal Received drops/recovery didn't result in any glitches at the sticks or stutters in the goggles. The receiver signal definitely shouldn't be doing that on a healthy setup. I've only ever seen the RX Signal Received value go low just before an actual failsafe in my own blackbox logs. I've never seen so many momentary drops like that before in a a blackbox log. If your logs from the weekend are still showing those symptoms then it means the reliability of the receiver remains a cause for concern.

I just checked BlackBox from today and from the weekend. The receiver graph is rock solid that location by the stadion obviously is not the best for flying. Here is some flight from today hope you like it and I think that is the time to earn some badges on the forum