50p wrong Playback

I use davinci resolve studio 15.2.1 and i tried a 1080p 50 frames per second clip from a gopro hero black 7.
Both, clip and timelime setting shows 50fps, but in the timeline the clip plays double time faster as it should be!
So a 1 minute clip plays in 30 seconds!!

Any ideas?

Something to try. Open a new instance of Resolve. Select the Media page and from your video files select one and drag it into the Master bin. You should get a pop-up dialogue that says "The clip(s) have a different frame rate than the current project setting". Click on the selection that says "Click on to change". Now see if the video will work.

Actually that is exactly what i did first! I thought, let's resolve solve it! Dropped the clip and the resolve created a timeline with "Timeline frame rate" and "Playback frame rate" with 50 fps. And even in the preview window it shows 50fps at playback.

So, i found a "solution": The "Timeline frame rate" setting was locked at 50 fps so i couldn't change it, but i tried to set the playback frame rate to 25 fps, which doesn't work either, and set it back to 50fps. Then it worked!
That doesn't explain why it didn't worked in first place when "Timeline frame rate" and "Playback frame rate" was already set to 50fps, so i think it is a kind of a bug.

Update: The false playback-rate is connected with the video monitoring setting. So if you want to have 50fps in the timeline format settings, you also have to choose a 50fps frame rate setting under video monitoring!