Premiere Pro Timeline freezes as soon as I import a 7th element to the project

[Kemstar72]

Hey guys
I have a problem:
I can no longer use Premiere normally.
Everything runs normally until I add a seventh element to the project. This sounds very strange, but that's how it is.

As an example, I have 1 video file, 3 sound files and 2 image files. I can work with them normally, but as soon as I want to use a seventh element the timeline freezes and I can't click on anything anymore. It doesn't matter if the seventh file is an adjustment layer, a video file, a sound file, an image, it doesn't matter at all. But as soon as I delete any of the seven elements from the project, no matter which one, everything works again immediately.

I have cleared the media cache, I have used older versions of Premiere. Then I tried once to create a new account on my Windows Pc with administrator rights. This is what a supporter from Adobe advised me to do. On the newly created admin Windows account I then ran Premiere, took seven image files from the internet and pasted them and there the problem did not occur. I don't know if it was because this time it was only image files from the internet, or if it really had something to do with the fact that I tried it with the new Admin Windows account. The nice Adobe supporter then told me that my Windows account was corrupted and that he couldn't help me and that I would have to contact Microsoft Support to have them fix my Windows account to solve the Premiere problem. I did so, but after many attempts with Microsoft Support, I still could not fix the problem. I even reset my entire PC (reset Windows) and reinstalled Windows. (With the option to keep all my private data, so no total reset). After that I also deleted my win.old folder, downloaded Adobe Creative Cloud again, installed Premiere and tried if the problem is still there. And it is still there. I am completely in despair. I reset my pc completely for nothing and now I have to invest hours to set up all programs and settings correctly again. I have an elgato streamdeck connected to the pc. Also an audio mixer (TC-Helicon GoXLR) but they have always been on my PC and have never caused problems when working with Premiere.

I just have no idea what to do, what is the problem here, where is this error coming from.

I'll add a video where you can see that at the beginning there are 6 elements in the project and everything works. Then I created a seventh element, an adjustment layer and after that you can see how nothing works properly. As soon as I delete any element and there are only 6 files again, everything works again.

[Ann Bens]

If the footage is variable framerate convert to constant framerate with Handbrake before bringing into Premiere.

[Kemstar72]

Thank you - But the framerates of the video files are always the same in my projcets

[Kemstar72]

Edit: I just found out, when I minimize the window the problem with the 7 elements is gone and everything works fine??? But when I maximize premiere pro to "fullscreen" it has this problem omg? 

What is this? 

[Kemstar72]

Edit Edit: I have 3 Monitors 

2x BenQ GL2450H Monitors  with 1920x1080 60hz

and my main Asus TUF VG27A 2560x1440 144hz 

When I maximize premiere pro on  both BenQ Monitors the problem is NOT there. Only when I maximize premiere pro window on the Asus Monitor this freezing are coming

[basil1891]

Make sure that NVidia G-Sync/ AMD Freesync is off in driver control panel

[Kemstar72]

I turned Gsync Off but the problem is still there unfortunatley

[basil1891]

Try on/off "Mercury Transmit" option (Preferences > Playback > Enable Mercury Transmit)

[Kemstar72]

Thank you I tried it, but problem is still there